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Cream Of The Crop - The Best Factory Jeep Parts

134 Ci Go Devil L Head Four Cylinder
Verne Simons
| Senior Editor, Jp
Posted May 1, 2013
Photographers: JP Magazine Archives

The Best OE Upgrades For Your Jeep

You can think of this as the unofficial Oscars of factory Jeep parts. The Emmys, Grammys, Teen Choice Awards, Video Music Awards, Screen Actor’s Guild Awards, whatever. Generally the parts we choose here are given this very unofficial Jp magazine award because they are the best from the factory. That could mean they are the strongest part, the longest lasting part, or maybe just the coolest part, but the part has to have been something widely available from the factory. This excludes some rare dealership-offered Jeep package and all its parts. This also excludes any cool parts from our friend the aftermarket, or other coach builders…just Jeep and Jeep parts. We are talking fairly available parts that you can dream about, look for at a junkyard, and may already have. What do we like? Here ya go. Disagree with us? Think we forgot something? Let us know. Send us an email or find us on the Web at jpmagazine.com, Facebook, Twitter, Face Space…whatever.

Front Axle
1. M-715 Dana 60
Pro: It’s big and beefy, has factory high steer
Con: Drum brakes, small 30-spline axleshafts (for a Dana 60), small axletubes (for a Dana 60), goofy wheel bolt pattern, stupid-wide width, closed-knuckle design, probably not much stronger than a later FSJ Dana 44
Found in: ’67-’69 M-715 and possibly some dual-rear-wheel FCs

2. Open-Knuckle Dana 44
Pro: Larger ring gear than Dana 30, strong housing for FSJ Dana 44s, 297x/760x-sized U-joints, external spline locking hubs (FSJ Dana 44s), comprehensive aftermarket support, JK Rubicons have larger U-joints for greater axle strength, wide range of ratios available
Con: Rubicon 44s have relatively thin axletubes and inner axle-Cs, TJ Rubicon 44s have smallish stub shafts
Found in: ’74-’91 FSJs, ’03-current Wrangler Rubicons

3. ’95-’99 High-Pinion Dana 30
Pro: High-pinion design is stronger in a front axle, 297x/760x-size U-joints (same as some Dana 44 fronts), more ground clearance than Dana 44
Con: Relatively thin axletube, weak inner-axle Cs, not as many gearing options as Dana 44
Found in: ’95-’99 Cherokees

Rear Axle
1. M-715 Dana 70
Pro: Huge, super strong
Con: Huge, goofy wheel bolt pattern, stupid-wide width
Found in: ’67-’69 M-715

2. J-Truck Six-Lug Dana 60
Pro: 35-spline, semi float
Con: 12-inch drum brake parts may be difficult to source
Found in: Early-late ’70s 3⁄4-ton J-trucks

3. Flanged Dana 44
Pro: Wide range of ratios available, large aftermarket support
Con: Not as strong as a Dana 60
Found in: ’70-’75 CJ-5, ’72-’91 FSJ, MJ and XJs with Metric Tonne package, ’86 CJ-7, ’97-’06 TJ, ’07-present JK

Auto Transmission
1. TH400
Pro: V-8 strong, great aftermarket support, available with AMC bolt pattern and Buick/Pontiac/Olds pattern
Con: No overdrive
Found in: ’76-’79 CJ, late ’60s-’79 FSJs, ’67-’73 Jeepsters

2. Torque Flight 727
Pro: Heavy-duty transmission, V-8 strong
Con: No overdrive
Found in: ’80-’92 FSJs

3. AW4
Pro: It’s got an overdrive, reputation for reliability, pretty good First gear ratio (2.80:1) for an auto and a 0.75 Overdrive ratio
Con: difficult to adapt for engine swaps, some require CPU
Found in: ’87-’01 XJ, ’87-’92 MJ, ’93 ZJ

Manual Transmission
1. Wide-Ratio T-18
Pro: Super-low First gear of 6.32:1, V-8 strength
Con: No overdrive
Found in: ’77-’79 CJs, ’76-’79 J-Trucks

2. NV3550
Pro: V-8 Strength, Overdrive
Con: Loud, pedestrian First gear ratio of 4.01:1
Found in: ’00-’04 six-cylinder TJs and ’00-’01 six-cylinder XJs

3. AX15
Pro: Overdrive, record of reliability
Con: Mild First gear ratio of 3.83:1
Found in: ’89-’95 six-cylinder YJs, ’97-’99 six-cylinder TJs, and ’89-’99 six-cylinder XJs

Transfer Case
1. Dana 300
Pro: Gear-driven, cast iron housing, good aftermarket support, heavy-duty, can be twin stick’d with independent front and rear shifting
Con: Jeeps with large tires and big power can break even the venerable Dana 300, short shaft ’80 version has little or no aftermarket support.
Found in: ’80-’86 CJs

2. NP241 or Rock-Trac
Pro: Factory 4:1, Factory slip-yoke eliminator
Con: Chain-drive, cast aluminum housing, some argue 4:1 is too low for general wheeling
Found in: ’03-’06 TJ Rubicons and ’07- Present JK Rubicons

3. 23-Spline NP231J
Pro: Easy to work on, common, strong aftermarket support
Con: Chain-drive, cast aluminum housing, long slip-yoke on rear output
Found in: ’88-’95 YJ, ’97-’06 TJ, ’87-’01 XJ, ’87-’92 MJ, ’93-’95 ZJ

Engine
1. High-Output 4.0L
Pro: Plenty of low-end torque, ability to go 300,000 miles, great horsepower for a six-cylinder
Con: Not a V-8
Found in: ’91-’95 YJ, ’97-’06 TJ, ’91-’01 XJ, ’91-’92 MJ, ’93-’98 ZJ, ’99-’04 WJ.

2. Dauntless 225 Odd-Fire V-6
Pro: Heavy flywheel, tons of low-end torque,
Con: Not a V-8, difficult to add fuel injection
Found in: ’66-’71 CJ-5, ’66-’71 CJ-6, ’66-’71 Jeepster Commando

3. 134ci Go Devil L-head Four-Cylinder
Pro: The little engine that started it all, easy to work on, reputation for reliability, nothing draws a crowd of Jeep junkies like a stock flattie still running an L-head
Con: Low power, old technology, getting hard to find good cores
Found in: ’49-’53 Jeep CJ-3A, ’48-’50 Jeepster, ’50-’52 Willys M38

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