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How To Buy A Used Pickup

Posted in Features on December 31, 2010 Comment (0)
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How To Buy A Used Pickup
Photographers: 4 Wheel & Off-Road Staff

Probably the most popular pickups ever produced are the '73-'87 Chevrolets. Classic styling and solid drivetrains are found in most of these rigs, and parts interchangeability is among the best of any vehicle line. Of course, these pickups do suffer from more than a few common maladies, but some years are better than others. In this story, we'll clue you in to what you should look for when buying one of these examples of honest American truck-building.

Engine Options The wide range of engines used is second only to the variations in compression and horsepower figures. In addition, not all engines were available in all of the weight ratings during all years. We've compiled a fairly comprehensive list of engines, but strange variations exist in the real world. As the EPA mandated better economy ratings and phased out leaded gasoline and California threw its regulations into the mix, compression ratios and power figures generally dropped, then started to rise as the technology improved to make these motors work almost as well as they used to. For instance, the lowly 305 of 1978 had a lame 8.4:1 compression ratio and is generally regarded as a poor performer. But by 1987, the little mill featured a 9.2:1 ratio, a 20hp gain, equally improved torque figures, and much better fuel economy.

The 305ci and 350ci small-blocks appear identical to the untrained eye, but the two or three stamped letters on the block in front of the passenger-side head above the water pump mounting can identify the displacement, but you may need a book that translates the code. If the motor is an '80-or-newer, the displacement is cast into the back of the block near the bellhousing mounting flange. The 350 is the 5.7L and the 305 is the 5.0L.

POWERPLANTS
Year Displacement Type Induction Application
'73-'75 250 I-6 1bbl K10/20
'76-'78 250 I-6 1bbl K10
'79-'83 250 I-6 2bbl K10
'85-'86 262 V-6 4bbl K10
'87 262 V-6 EFI V10
'73-'76 292 I-6 1bbl K20
'77-'85 292 I-6 1bbl K20/30
'77-'79 305 V-8 2bbl K10/20
'79-'81 305 V-8 2bbl K10
'81-'86 305 V-8 4bbl K10
'87 305 V-8 EFI V10/20/30
'73-'76 350 V-8 4bbl K10/20
'77-'81 350 V-8 4bbl K20/30
'82-'86 350 V-8 4bbl K20/30
'87 350 V-8 EFI V10/20/30
'82-'86 379 V-8 Diesel K10/20/30
'75-'76 400 V-8 4bbl K10/20
'77-'80 400 V-8 4bbl K20/30
'77-'86 454 V-8 4bbl K30
'87 454 V-8 EFI V30

Models Available The "standard" pickup is somewhat of a misnomer; so many options and styles were produced that the standard two-door cab with a Stepside bed is simply one of many styles. Two basic body designs were available: the '73-'80 with square hoods and fenders, and the '81-'87 sloped-nose style. Spotting weight ratings was simple back then: 1/2-tons were K10s, 3/4-tons were K20s, and the 3/4-tons were K30s. The exception was in 1987 when they changed the K to a V, a prelude to the massive body and mechanical changes of the '88 model year. Beds came in long and short with either the Fleetside or Stepside design, though shortbeds were used only on K10s. The "Big Doolie" with dual rear wheels was introduced on the '77 K30 truck. In addition, the Crew Cab and Bonus Cab was offered on the K30-the Crew Cab had rear seats and the Bonus Cab had only an open storage area. A factory extended cab was never available with the '73-'83 trucks.

Trim levels started with the Custom and ended with the Silverado package with all the options and goodies, but the basic mechanicals stayed the same. However, the weight ratings were more of a factor in model availability, as K10 models never received a dualie or Crew Cab configuration. And all of the styles had little relation to the two-wheel-drive options, as C30 pickups with 454 power were available long before the big-block K30 made the scene in 1977.

Tranny Choices With only three manual transmissions and three automatics to chose from, it's pretty hard to make a poor choice. The three-speed stick was shifted on the column and is the least common (and least desirable) choice. A manual four-speed with overdrive was made for a few years, but it's also not very common. The manual four-speed SM465 is a floor- shifted, granny low box that has a virtually untarnished reputation and is a favorite of gear-grinders. The TH350 and TH400 are almost indestructible if not overheated and are arguably two of the best autos ever produced. The 700-R4 four-speed auto features an overdrive gear for highway cruising and mileage, but during the first few years of production, it was plagued by problems that have since been sorted out.

TRANSMISSIONS
Year Model Engine Type/Model Ratios (First, Second, Third, Fourth, Fifth)
'73-'80 K10/20 All Three-speed manual 2.85, 1.68, 1.00
'81-'84 K10/20 250, 305, M15 3.50, 1.68, 1.84
350 three-speed manual (2.85 or 3.11 First gear also available)
'73-'87 K/V10/20/30 All SM465 6.55, 3.58, 1.70, 1.00
four-speed manual
'82-'87 K/V10/20 All MM7 N/A
four-speed manual OD
'73-'80 K10/20 All TH350 2.52, 1.52, 1.00
three-speed automatic
'77-'87 K/V20/30 All TH400 2.48, 1.48, 1.00
three-speed automatic
'82-'87 K10/20 All 700-R4 3.06, 1.63, 1.00, 0.70
four-speed automatic
'81-'87 K10 Diesel TH400 N/A
three-speed automatic

T-Case Tips Only three different transfer cases were used from 1973 to 1987: the NP205, NP203, and NP208. Only the NP205 is available in all these years, and it's regarded as the toughest style around for regular pickups, as evidenced by the usage in the 1-ton models. The 205 is a simple, relatively light geardriven unit with part-time operation. It's identifiable by the three-bolt retainer (seen on the back of the case) that holds the shaft that goes through the center of the cast-iron case. From '80-'91 the 3/4-ton and 1-ton versions used a long slip-yoke-style extension housing similar to that seen on NP208s.

The full-time NP203 used from 1973 to 1979 was a heavy (heavy) but durable chaindrive style identified by the two-piece tailhousing made of iron or aluminum. Both the NP203 and the NP205 suffered from a 2.0:1 low-range ratio, which was deemed adequate for the era when low axle ratios were available.

The chaindrive, part-time NP208 was introduced in order to save weight. The NP208 low range is a respectable 2.61:1.

TRANSFER CASES
Year Model Type Drive Low Ratio Applications Engine/Transmission
'74 203 Full-time Chain 2.01:1 K10/20 All except six-cylinders
'75 203 Full-time Chain 2.01:1 K10/20 V-8 auto
'73-'79 203 Full-time Chain 2.01:1 K10/20 V-8 auto
'73 205 Part-time Gear 1.94:1 K10/20 All
'74 205 Part-time Gear 1.94:1 K10/20 Six-cylinders
'76-'79 205 Part-time Gear 1.94:1 K10/20/30 Manual only
'80 205 Part-time Gear 1.94:1 K10/20/30 All
'81-'86 205 Part-time Gear 1.94:1 K30 All
'87 205 Part-time Gear 1.94:1 V30 All
'81-'86 208 Part-time Chain 2.61:1 K10/20 All
'87 208 Part-time Chain 2.61:1 V10/20 All
AXLES AND RATIOS
Year Model Front End Rear End Available Ratios
'73-'74 K10 Dana 44-F 12-bolt 3.73, 4.10
'75-'76 K10 Dana 44-F 12-bolt 3.07, 3.73, 4.10
'77-'79 K10 Dana 44-F 12-bolt 2.76, 3.07, 3.73
or 10-bolt
'80-'82 K10 10-bolt 12-bolt 2.76, 3.07,
or 10-bolt 3.42, 3.73
'83-'87 K/V10 10-bolt 10-bolt 2.56, 2.73, 3.07,
3.42, 3.73
'73-'76 K20 Dana 44-F 10 1/2-inch 4.10, 4.56
14-bolt
'77-'79 K20 Dana 44-F 10 1/2-inch 4.10, 4.56
10-bolt 14-bolt
'80-'82 K20 10-bolt 10 1/2-inch 4.10, 4.56
14-bolt
'83-'87 K/V20 10-bolt 9 1/4-inch 3.23, 3.42,
14-bolt 3.73, 4.10
'77-'87 K/V20 Dana 60-F 14-bolt 4.10, 4.56
'77-'87 K/V30 dualie Dana 60-F Dana 70 4.10, 4.56
Crew Cab

Common Problems As much as we like these pickups, they suffer from certain problems. All old trucks do, but it seems like the '73-'87 Chevys are most problematic-we're probably just aware of more problems because these trucks are so common.

The biggest safety concern is the steering box mounting area which fatigues and cracks, causing the steering box to loosen and fall off. The rear of the frame cracks near the shock mounts and crossmembers when subjected to severe service. Door hinges wear out with regularity, especially on the driver side, and, in wet climates, rust forms easily at the rear of the front fenders. Unless the hood hinges are frequently lubed, they seize up and invariably bend the hood in the middle. And, of course, the wooden beds fall apart if not taken care of; they were discontinued in 1980.

Differentials Front and rear axle styles didn't vary greatly except for weight ratings between models, and most of them are easily interchangeable. The cover bolt count and design are the easiest ways to identify the model, as is the amount of wheel studs used per wheel. Front axles for K10s and most K20s were either the Dana 44 with 10 bolts on the cover and an angular shape, or the Corporate 10-bolt with an ovalish cover and 10 bolts. The 10-bolt and Dana 44 used ball joints in the steering knuckles with a three-bolt steering arm. The K10 series used six-lug wheels, and the K20s were fitted with eight lugs. The K30 models received Dana 60 front axles with a 10-bolt angular-shaped cover that's much larger than the 44. The wheels were eight-lug but with 9/16-inch studs instead of the K20's 1/2-inch style. Chevy Dana 60 steering arms were fitted to the knuckle with four bolts instead of three.

Rear axles used on the K10 were Corporate 10- or 12-bolt designs, with the identifying features being the number of bolts in the cover. The K20 and K30 used a 14-bolt cover, except for the dualie Crew Cab, but two different shapes of covers and ring gear diameters were used. The 9 1/2-inch 14-bolt had a smooth-sided cover, while the larger 10 1/2-inch style was sharply angular and had a bolt-on pinion bearing support unlike the smaller style. Except for the 10-bolt unit, these axles are more than adequate for most types of 'wheeling. And the Crew Cab "Doolie" used the dual-rear-wheel Dana 70. Dualie front Dana 60s were also slightly different from single-rear-wheel versions.

The Best Years Every 'wheeler will have an opinion on the best factory-equipped Chevy pickup. We talked to Mike Boyd at Four Wheelers Supply and asked what he would chose. Boyd has been in the aftermarket industry for many years and also has an extensive background in 4x4 truck recycling. He chose three different pickups according to the weight ratings and mechanical accouterments, since that's what most 'wheelers consider rather than the style of the grille or shape of the lug nuts when buying a 4x4.

1/2-Ton K10-1979 Like the other truck producers, this was the high point in Chevy quality, style, and componentry. Trucks were available with a 350 engine, a four-barrel carb, and a part-time 205 transfer case with the SM465 four-speed. The front axle wasn't a Dana 44, but the Corporate 10-bolt is nearly as strong, and the rear axle was nearly the last of the beefy Corporate 12-bolt units produced.

3/4-Ton K20-1984 Once again, this was the last of its kind. The 350 engine was devoid of catalytic converters and easily passed federal emissions standards without lots of emissions junk hanging from the motor. The super-strong TH400 automatic was hooked to the NP208 transfer case with the low range of 2.61:1. While the front axle was a regular Corporate 10-bolt, the available rear axle was the large 10 1/2-inch-ring-gear 14-bolt.

1-Ton K30-1987 For all-out heavy-duty use, this pickup is a clear winner. The massive 454 engine was available with a Quadrajet carb or fuel injection and was offered with the TH400 auto and NP205 transfer case. The front axle was a Dana 60, and the rear was the much-adored Dana 70 in the dual rear wheel configuration. Add all that to the fact that a four-door cab and an 8-foot bed were available, and, except for a lot of size and weight, this is one fine factory truck.

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