Bob,
I've been on the road, so I didn't have much time for forums. For most 5-speed diesel LUV/P'up owners, the 3.73 is the optimum rear end. Those came ONLY in diesel LUVs and P'ups that had 5-speed transmissions. That 4-speed gas LUV you're looking at should be a 3.41. Some owners have done this swap, and they like it. I don't recommend it unless your engine is still strong, and you live in a really flat area. Otherwise, you won't have the power for 5th. And, if you ever upgrade to the '86-'95 gas transmission, it has higher gears in 1st, 2nd, and 3rd--so a 3.41 would make it even slower off the line.
You only have 3 bolt-in choices: 3.41, 3.73, and 4.10. In the 2nd-gen LUV and all P'ups, the 3.41 was in 2wd 4-speeds, gas and diesel. The 3.73 was only 5-speed diesels. The 4.10 was in gas 5-speeds, all automatics (gas and diesel), and all 4wd trucks (gas and diesel). You do NOT need the whole axle, but the axles have to come out to remove the chunk.
If you want a 3.73, contact
sqdeb@yahoo.com. They just might have one. I got mine from them, and it was very reasonable. They're great people.
Jack
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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.comIsuzuPup.com