Cliff Notes
The Project: I have a '83 CJ-7 and a '00 Explorer 5.0L V-8 that want to be together. I found a very pretty NP435 Ford four-speed on Ebay for $50. I believe I can overcome the technical obstacles to the swap, but I'm having second thoughts about the transmission. I know people love the old granny tranny off-road, but I'm hearing it shifts like a dump truck on the street with long, heavy throws. First gear is useful only for pulling stumps, the ratios are too wide, not to mention the Rat-Fink shifter.
What It's For: My Jeep lives in the middle of the Mid-lantic Megalopolis. The black helicopters have taken over Paragon, so the closest dirt road is now way up at Rausch Creek. The CJ goes everywhere (unless it's raining, 'cause there might be nothing left but a rust stain). Stirring the pot in traffic gets old, even with a civilized stick, so I'm thinking an automatic might be better for the Jeep after all. The 4R70W auto that was attached to the Exploder engine got away, but I could probably scrounge another one up.
Questions: Is the big computer-driven slushbox going to leave room for my Dana 300 and a working rear driveshaft? I'd like to have a highway gear, so a smaller three-speed auto like a C4 or C6 is less than ideal. Is the NP435 really that bad on the road? Are there ways to teach the old four-speed better manners? I've seen a shift lever kit for a T176 that looks identical to the pieces on the NP435. Can I use that to tighten up the action? The lever I have could be used for pulling very large wine corks.
Speaking of driveshafts, what are the chances that the NP435 with a 6.5-inch bellhousing and a 4.25-inch adapter will bolt to the Dana 300 where it sits? It looks pretty close.
Tech Notes: It's an '83 CJ-7 with a 258 six, TF999 automatic, Dana 300, Dana 30 front axle, AMC 20 rear axle, 3.55:1 gears. (I know, but some P.O. swapped in a set of narrow axles out of a '77. Cute, huh?) Has 31-inch tires, will probably not go bigger than 33-inch, about 2 inches of lift from shackles and what looks like some kind of replacement leaves.
I have all the Explorer harnesses right back to the taillights, the computer (the '00 V8 Explorers all had automatics), the relay box, and the OEM starter. For the NP435, I have a Ford F-series bellhousing with hydraulic clutch linkage and an AA adapter; still need a truck flywheel, clutch, and starter. I plan to use FRPP shorty headers that fit the Explorer GT40P heads, but I don't know if I will need a mini starter to clear the headers.
The Jeep only has to pass '83 emission standards (the 258 needs a pity pass to get through DMV here), so I don't much care about codes or check-engine lights.
Jay McMillan, Wilmington, DE
I'm a huge fan of the NP435. In fact it's my all-time favorite four-speed. My '85 Dodge Ramcharger had one (same 6.68:1 First and other gear ratios as Ford, but different bellhousing/t-case bolt patterns). I bought it with 73K on the odometer and then put an additional 200K on the truck with zero tranny problems. The last 100K were with 37-inch and larger tires and monster off-roading. I think I only changed the oil in it once. Yeah, it shifts like a bread truck, but you get used to it. I got to the point where I could actually power shift that sucker at LACR drag strip. Bulletproof, durable, and just an all around good unit in my opinion.
As for the Explorer tranny, guys swap them out for TH700R4s, so that should tell you something. I'm sure they're fine in an Explorer, but most Ford autos don't like to run at angles. Regardless, I think you'll be able to make a rear driveshaft work in that as long as you keep the lift somewhat small. You can also take the engine swap install as an opportunity to move the engine forward to make more rear driveshaft room.