Transmission Swap and Install Guide

In the 4x4 world, gearing is the stuff dreams are made of. Gearing can compensate for an anemic powerplant, give a rockcrawler greater crawling ability, provide the low-end grunt needed to get a heavy load moving, and enable the engine to lope at freeway speeds for better fuel economy. One of the best ways to obtain all of the above in a vehicle that lacks any of these capabilities is to swap in a different tranny. We’re going to take a look at some of the parts, procedures, and requirements for swapping five of the most popular trannies--the NV4500, the T18, the SM465, the TH350 auto and it’s heavy-duty brother the TH400, and the TH700-R4 into Chevys, Fords, and Jeeps.

If you need more information on the specs of these trannies and why they’re popular, check out past issues of 4-Wheel & Off-Road. We’ve broken down this article into three vehicle-make sections and then listed the specifics for each tranny within the section, so there’s no need to wade through a pile of info on other vehicles that you don’t care about. You’ll also find that most of the information in the following paragraphs consists of what parts and adapters are needed for various swaps, what type of tranny to look for, and all the basic stuff needed to physically bolt a nonstock tranny between an engine and a transfer case.

In some cases, there’s not a lot of information on all the auxiliary but still vital parts needed to complete a swap, such as the clutch linkage, the crossmember alterations, and the transfer case shifter control mods and so on. Why? We could say there’s no way we could fit all that information in the limited space here (which is true), but the main reason is that, due to the different vehicle and drivetrain combinations, virtually every tranny swap is different. Each person that attempts a swap will run into problems or concerns that are unique to his or her application, and these will need to be addressed on an individual basis.

Sometimes a company such as Advance offers items to address specific situations, and whenever possible we include this information in the story. But in many cases it’s up to the swapper to make all the parts and pieces work. Therefore, understand what you’re getting into before you start, and we’d strongly recommend having a fair amount of fabricating and adapting experience under your belt or a good support group--such as Advance Adapter’s tech line and a local expert--before you begin. Special thanks to Chris Hansen at Advance Adapters and John White at JB Conversions for sharing with us their invaluable knowledge and expertise.