The transfer case is the heart of the four-wheel-drive system in your rig. Naturally, this means that you want one that offers outstanding function and exceptional dependability. But with an array of transfer cases available, there is a question that begs to be answered. Which have proven themselves to be rugged and durable?
To answer that question, the staff here at Four Wheeler met around the ol' roundtable of discussion (which is actually square) and created a list of our 11 current favorites. Surprisingly, there wasn't much debate because we all chose basically the same units. In this list (which is in no particular order), you'll find some familiar models that are proven performers in the 'wheeling world. You'll also see a few relative newcomers that take transfer-case technology and beef to a whole new level. One thing all of these transfer cases have in common is that we'd bolt any one of them under our rigs. As a matter of fact, some of us have.
Dana/Spicer Model 18
Why it's cool: Over 30 years. That's the production span of the Model 18, and that is an incredible lifespan that speaks volumes about its reliability. This cast-iron, offset-drive, geardriven, two-speed 'case is found in '40-'71 Jeep vehicles as well as some International trucks. Our own Tech Editor Sean Holman has this 'case in his '51 Willys.
There are a few versions of the Model 18, with the most desirable being the "large case" version found in '66-'71 vehicles behind the Buick V-6 engine with the T-86 or T-14 transmission. We've seen the Model 18 subjected to more power than it was originally designed for, and for the most part it handles the power without complaint. However, because the Model 18 is a side-drive 'case, the intermediate gear is always under load. The result is that the bearings and intermediate shaft are prone to wear.
How you can get one: These are very hard-to-find units. However, Novak Conversions has had some luck in procuring these units for customers. If you already have one, they offer complete rebuild kits for the Model 18 and they offer a special hardened intermediate shaft that holds up extremely well to wear. High Impact Transmission & Gear also has rebuilt units and rebuild parts. Advance Adapters offers adapters to mount the Model 18 to a variety of manual and automatic transmissions.
NP205
Why it's cool: The NP205's ruggedness is truly legendary. An indicator of this is the fact that 16 of the 30 Top Truck Challenge competitors from 2004 to 2006 have had a 205 integrated into their rigs in some fashion.
The 205 is a geardriven unit that has come standard in many Dodge, Ford, GM, and International trucks. It has a low-range ratio of 1.96:1 and an overall length of approximately 14 inches. Be aware that there are many different versions of this unit with a variety of input shaft and bolt pattern configurations. There are also "married" and "divorced" versions. Gobs of aftermarket upgrades are available to make the 205 even better, including twin sticks, a Klune underdrive, and the popular Off Road Design "Doubler," which melds the gearbox section of an NP203 to a complete 205 case to create a 4.0:1 'case. If you're hunting junkyards for a 205, Stephen Watson of ORD notes that it's important to get all of the parts for the unit-even the adapter, as these can run $250-$300 by themselves.
How you can get one: Off Road Design offers a wide range of rebuild kits and parts as well as completely rebuilt 205s with a new 32-spline front output shaft and a fixed-yoke rear output shaft. Vince and the team at 4xHeaven can also set you up with rebuild parts, or they can rebuild your 205 for you.
Dana 20
Why it's cool: One of our editors had a Scout and he swears he couldn't kill its Dana 20, though he unwittingly tried many times. The cast-iron-cased, geardriven, 2.0:1 low-range Dana 20 was found in a variety of vehicles including Jeeps, Chevys, and Fords in addition to the aforementioned IHs. It was a follow-up to the Dana/Spicer 18 and some parts interchanged. Unlike the Dana 18, the 20 had a more direct method of drive in high-range. The Jeep and Scout Dana 20s were the most similar of the bunch.
How you can get one: The folks over at High Impact Transmission & Gear have rebuilt Dana 20s waiting for a home, and they also have a wide range of rebuild parts. 4xHeaven can also help by rebuilding your Dana 20 or by providing rebuild parts.