New Process NP435
Donor Vehicles: Ford trucks from '66-'92 and Dodge trucks from '64-'93
Swap into: Any Jeep that needs a bulletproof transmission with a low First gear
Identify: It is 107/8 inches long with a cast-iron case and an aluminum top cover. There are three different First gear ratios available: 6.68, 4.90, and 4.56:1. Spin the input in low to count output revolutions.
Gears: 6.68, 3.34, 1.74, 1.00 (First through Fourth); 8.26:1 Reverse
Pros: Similar weight and length as the SM420, but much more readily available in junkyards, and it is 60lbs lighter than the SM465.
Cons: Aluminum top cover stick shift retainer pins can strip out, or wallow out holes over time, multiple First gear ratios and output/input configurations can make finding the right one difficult.
Comments: This is basically Ford and Dodge's answer to the SM465. With its low First gear, ultra low Reverse gear and strength make it a good candidate for any Jeep, but especially one with a Ford or Dodge engine.
New Venture NV4500
Donor Vehicles: '93 and up Chevy truck, '95-'04 Dodge truck
Swap into: A Jeep with enough wheelbase to handle it that needs a heavy-duty five-speed Overdrive transmission.
Identify: It has a cast-iron case, an aluminum top cover, an aluminum tailhousing, PTO ports on both sides, its 18.9 inches long, has either 6.34 or 5.62:1 First gear, and weighs about 200 pounds.
Gears: 6.34, 3.44, 1.71, 1.0, 0.73 (First through Fifth); 6.34:1 Reverse
Pros: Big, beefy truck-style transmission like those listed above, but with the addition of an Overdrive for better street manners.
Cons: Big, heavy, and somewhat balky shifter movements make for fitment issues and more effort to drive every day. More transmission than 80-percent of the Jeeps out there need, nonetheless popularity drives up the price. One of these could easily run you double what its four-speed counterparts would cost.
Comments: It's got beef, that's for sure, but some units develop Fourth and Fifth gear issues with age, so beware of the screaming deals. For the amount these things demand make sure that it is ready to go as-is because opening it up and rebuilding it isn't that cheap either. And, finally, make good and sure you really need something this big. Most Jeeps don't.
Aisin-Warner AW-4
Donor Vehicles: '87-'01 XJ/MJ, '93 to '94 1/2 ZJ with the six-cylinder engine
Swap into: Any '87 and up Jeep that came with an automatic transmission and a 4.0L engine.
Identify: Look under a Cherokee with an I-6 and an auto, and there you go. It is 25 3/8 inches long, has a removable bellhousing, has the standard 6-bolt flange on the tailhousing, and a 1/4 pie-shaped neutral safety switch on the passenger side near the bellhousing.
Gears: 2.80, 1.53, 1.00, 0.75; 2.80:1 Reverse
Pros: Well respected Overdrive automatic transmission with a stand-alone controller that is a bolt-in to most six-cylinder Jeeps with Jeep parts that can be found in the junkyard.
Cons: Not a good swap into a Jeep with a V-8 or stroker, it can run hot when wheeling: a larger cooler is a necessity if a lot of time is spent rockcrawling or towing, and its longish length can lead to a really short driveshaft with goofy angles in lifted Jeeps with stock wheelbases.
Comments: With an Overdrive, this transmission is a more livable automatic than any YJ or early TJ slushbox, and it wheels better than the four-speed in the later TJs. However, if you swap this transmission into an automatic-equipped TJ, you will end up with a check engine light because it won't talk to the TJ computer and you'll need to swap your stock ECM out for a computer out of a manual transmission TJ. When you pull the AW-4 from the donor, make sure to get the TCM (transmission control module) as well. The TCM is often found behind the glove box or behind the dash near where the driver's knee would be.