Budget Drivetrain Swapping
If there has been one underlying theme to our '68 J2000 project it's been moderation. In Part II, we bolted on some simple Hell Creek Suspension 4-inch lift springs and 33-inch Pro Comp AT tires. In Part III, we rebuilt of a pair of Dana 44 axles with 4.56 gears and Eaton Truetrac differentials. Last time, we covered the axle installation. All in all, we've tried to use non-exotic and junkyard parts where applicable. So when it came time to gather parts to replace the tired 232 engine and insufficient T-14 tranny, we shelved thoughts of high-horsepower V-8s and crazy overdrive automatics.
With fuel prices climbing higher and faster than an SR-71 Blackbird, a fuel-efficient 4.0L Jeep engine seemed a sane choice. Plus it would bolt right to the 232's engine brackets. The 4.0L's 190 hp and 225 lb-ft would move our J-truck well, and when coupled with an NV3550 five-speed, would probably knock down decent mileage numbers. We're hoping for 18 mpg with our 33s and 4.56 gears.
We began searching for a wrecked Wrangler or Cherokee from which we could pirate the whole drivetrain, but after a few months of failure we gave up and put in a phone call to Scotty's Jeep, Truck & 4x4 in Fontana, California. Scotty's has a massive Jeep wrecking yard and keeps a huge inventory of all sorts of Jeep parts on hand and ready for shipping. The company had a good 4.0L taken out of a '92 XJ with a five-speed transmission. We got the engine, accessories, wiring harness, and computer and had the gang at Scotty's load it into the back of our J2000.
As for transmissions, we stumbled across several AX-15s for sale, but we never would have trusted the relatively light-duty transmission with some of the heavy hauling and moderate towing we expect this truck to do. Instead of going the junkyard transmission route, we placed a call to Advance Adapters for one of the company's remanufactured NV3550 transmissions and everything we'd need to mate it to our 4.0L. That included a bellhousing, slave cylinder, release bearing and arm, and slave cylinder-to-clutch master cylinder hose. But you'll see more on that in a future issue.
As for the T-case, we originally obtained a brand-new NV231 from Advance Adapters since we had planned on using a late-model J-truck front axle with a driver-side drop. But when we wound up using a passenger-side drop Dodge front axle, we returned the NV231 and began looking for an early '80s Dodge NP208 T-case. The Dodge NP208 bolts right to an NV3550 tranny and comes factory with a fixed yoke on the rear so there's no need to buy expensive adapters or slip-yoke conversion kits. We bought a used NP208 online and took it to M.I.T. Drivetrain Specialists in El Cajon, California, for a full rebuild to ensure years of trouble-free service.
Read on to meet our new drivetrain. And tune in next time to see our engine get prepped for installation into our vintage pickup.