QI love the mag, the online articles, and so on. Thank you! I decided to mall-crawl my ’68 half-cab Bronco that I originally intended to build as a crawler. Early Broncos are becoming too valuable for me to feel good about beating it to death. This left me with nothing to wheel. Since that wasn’t going to work, I recently picked up a ’83 CJ-7 roller with a 383ci stroker GM V-8, military kingpin Dana 60 front axle, and a 14-bolt rear axle with a Detroit Locker. Both axles have 4.56:1 ratio gears. The transmission is a T-19 manual and the transfer case is a Dana 300. It also came with some extras like a Blue Torch Fabworks full width kit on the front, some Poison Spyder rock sliders, and so on, but, it’s basically trash otherwise. The motor and drivetrain are not installed and the tub and frame are Swiss cheese.
To solve this problem, I picked up a buddy’s ’85 CJ that is in much better shape to swap all the goodies into. I’ll be swapping things over one major component at a time, starting with the axles and drivetrain. I plan on building a crawler first and foremost, with (very far into the future) dreams of Moab, Fordyce, and the Rubicon.
Assuming I go with the
383 Chevy V-8 as my powerplant, should I stick with the T-19 and Dana 300 or go with the NP435 and NP205 that I originally bought for the Bronco? I know I’ll need a Chevy NP205, but that’s not a deal breaker. I’m more worried about overall difficulty of the swap, clocking of the NP205, weight, and just fitting it all in nicely.
Yes, there are a million threads on the T-19 versus the NP435 and the Dana 300 versus the NP205, but I’d rather get an answer from true experts that I can trust. My NP435 and NP205 have the lower spline count on the shafts, so they are not as desirable, but I’m OK with upgrading those if need be. I’m aware of the SM420, but I can’t find one. What say you? All advice and opinions are appreciated.
WILLIAM COVERT VIA EMAIL
AA lot of the drivetrain decisions you need to make will be based on tire size and driving style. The Dana 300 is a great compact transfer case that will typically allow you to retain the factory CJ-7 wheelbase, if that’s the plan. Given that you intend to run a 1-ton Dana 60 front axle and a 14-bolt rear axle, it’s likely safe for me to assume that you plan to run tires that are at least 37 inches tall and possibly much larger. With the power of the 383 V-8, overall weight, direct drive of a low-geared manual transmission, and the assumption of tires larger than 35 inches, I’d be a little nervous about using the Dana 300 transfer case. Could you make it work? Of course, but it will require sane driving and proper driveshaft angles that don’t allow binding under load or when the suspension cycles. This can be tricky, especially with the axlewrap that leaf springs usually allow.
The Dana 300 front and rear outputs are usually the first to fail on a build like this and it’s typically because of driveshaft binding. If you are careless with your driveshaft angles and driving habits, I’d recommend installing heavy-duty 32-spline outputs front and rear on the Dana 300 right away. JB Conversions (jbconversions. com) offers front and rear 32-spline outputs. Advance Adapters (advanceadapters.com) and Novak Conversions (novak-adapt.com) both offer a heavy-duty 32-spline rear output for the Dana 300. Be sure to check the Dana 300 model before ordering parts. There are two versions that came in Jeeps and one International Harvester version. The less common ’80 Jeep Dana 300 can be identified by a shorter rear output housing assembly that measures in at about 3.5 inches. The ’81-’86, and most common Jeep Dana 300, has a rear output assembly that measures in at about 5.5 inches. The International Harvester version of the Dana 300 has a Texasshaped mounting surface (similar to the Dana 20 and Spicer 18) instead of the round mount- ing face found on the Jeep Dana 300. Not all parts will interchange, so order your aftermarket outputs carefully.
The NP205 is an extremely heavy-duty transfer case that is more up to the strength level of your other drivetrain components than the Dana 300. However, it’s very large and will likely require that you extend the wheelbase of your CJ-7 to have proper functional suspension movement and driveshaft angles. The only major downfall of the NP205 is the pathetic 1.96:1 low-range gear. This makes the NP205 less desirable for a 4x4 that you plan to do any kind of slow technical rock work with. Of course, there are solutions. Offroad Design (offroaddesign.com) offers several different crawl boxes that can be added in front of your NP205 to get the gearing down lower. You’ll likely need to extend the wheelbase of your Jeep several inches to allow for the added length of an Offroad Design Doubler or Magnum underdrive unit. If you only want to extend the wheelbase a few inches, JB Conversions offers the Lomax kit to convert your NP205 to have a 3:1 lowrange gear. This setup would keep the NP205 transfer case at its factory length.
As for the transmission, the T-19 and NP435 are both great. Their adaptability will depend on what they originally came out of. I think you could simplify your swap and reduce costs significantly by sticking with a GM manual transmission, especially if you plan to run the GM NP205 transfer case. The SM420 and parts for it are getting harder to find, so it’s not the best choice. You might want to consider the GM SM465. It came mated to the NP205 from the factory. If you can find this combo used you’ll save a lot of money on adapters and it will bolt right up to your GM engine with a factory bellhousing. Ultimately, trying to adapt your Ford transmissions to your GM motor and transfer case isn’t all that cost effective. Just because you already have the components doesn’t necessarily make them an ideal swap. If you decide to keep the Dana 300, just run the T-19 that it’s already mated to. Make sure it’s a T-19 and not a T-18 before ordering any parts.
Normally, you should mock up the axles first with whatever wheelbase that you have planned for your project. However, in your case, I think you will want to mock the engine, transmission, transfer case, and any crawl boxes into place before settling on a wheelbase. It will take some trial and error and you will likely have to move things around a few times to make it all work properly. Don’t forget to take the radiator, fan, exhaust, driveshaft clearance and angles, steering, and so on into consideration before final welding of all of the engine and suspen-