We have the D100 running great with the 360 magnum that has a carb on it. We ended up putting a 46rh transmission in it and used switches to activate the overdrive and lockup converter. It is extremely high geared. I believe it’s a 2.90 or higher. I would like to go to a 3.55 to 3.90 gear with a sure grip. What would be a good donor to look for. I would like to find a complete rear axle instead of trying to set up the lash on a new gear set.

 

best to look for a 90-93 ramcharger. anything older and it will likely have the 3.21 gears like you likely already have. 3.90 or 4.10 gears are uncommon to be found in 1st gens from the factory unless you got something that was built as a work truck but even then you would likely only find them in a dana 60. ramchargers are the ones you are most likely to find a LSD in. both my ramchargers do but 1 has 3.21 gears and the other has 3.55 gears. you could always get the rear axle rebuilt. not exactly the cheapest route but will get exactly what you want that way especially if you want 3.90 or 4.10 gears.

 

Check what rear you have before you order gears, my 91 D150 has an 8.25 10 bolt rear with 3.55s open, I bought a locker for a 9.25 was gonna send it back but I'm gonna keep it and upgrade to a 9.25 I don't think the 8.25 axels will last long with my 360 mag build. I wouldn't think they would put such a small rear in these trucks, but they did. Unless I find a Ford 9" might be my better bet, seems to be a few on CL but they got the small Ford bolt pattern Which means different wheels. Might be worth upgrading the whole rear. I found a 9.25 l/s with 3.55s from a 94 but my locker won't work in the carrier. Not sure if a 2nd gen rear would fit in the 1st gen without moving the spring mounts, I know the shock mounts would need to be cut off, I'd like to find one with disc brakes.

 

These may be 3.21. I am used to GM transmission. I do not know how the gear set 1-3 are. I do know you really need to be around 70mph before going to OD and lock the converter around 80mph. I am not even joking about that I was using gps for a Speedo. The newer transmission had an electronic speedo driver. I drove it on a 12 hour road trip and buzzed along at 85mph with zero issues. It is a total pig with the gears in it now. We pulled the engine from a Dakota that had 3.73 gears and it was pretty peppy. The Dakota was not a whole lot lighter. It was an extended cab loaded with a full tool box in the bed. I really appreciate the help from you guys. I didn’t know if a later model 4x4 had a rear end I could look for and try to swap it in without a huge hassle. My son in law is dead set on keeping it as stock appearing as possible. Personally I would lower it a foot and put a modern wheel on it. LOL

 

Pay particular attention to the placement, above or below the spring. My 91 is below the spring. if you get a 2nd gen rear and get a 2 wheel drive, it will go above the leafs, a 4x4 rear will mount below the spring. If you want factory ride height you'll need one that will mount the same.

Gears make or break an engine build. I was wanting to go with 4.10s but I think they are too low, I'm looking for 3.7 or 3.9 ratio. I just tossed a set of 29/12.50r 15 Hoosier pro streets on the back, with a set of 295/60r15s on the front to give it that old school muscle car look.

 

with 3.21 gears and overdrive/lockup it should run very happily in the 70-100mph range. probably best to go with 4.10 gears if you get it rebuilt. they would likely keep the truck happy at the 60-80mph range. would also make it a lot more fun off the line.

 

I will look around a little before we get new gears and posi. I think it needs a 3.90 to 4.10 gear. It spends most of its time just cruising around the military base. He is going to be in for the foreseeable future. I want it to be more responsive. There is an 1/8mile track close by. If it does decent we can lock up the converter for a road trip. From what I read I believe I can spray it a 100-125hp shot to get a decent number out of it. I think it will go 7.90s with that little bit of help. LOL! I am just trying to manage the budget for the kids if I can. I spent almost $600 on my 10 bolt. A donor rear end was what I was after. Thanks for the input. I have learned a lot on the forum.

 

if you got access to a welder and know how to weld you could look into seeing what it may take to get a 2nd gen 9.25 to fit. it is about the only that you may find 3.90 or 4.10 gears in from the factory that might also have a LSD. you would want to be looking for a truck that has the off road package. i think the bumpers are usually painted the same color as the body on these trucks. i think the axles are a bit wider on the 2nd gens so may need rims with less backspacing. otherwise most 1st gen trucks have 3.55 gears or 3.21 gears