1991 FJ80 rear driveshaft length and viscous coupler

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Hi all, I've had a clunk for many years in my 1991 land cruiser, about 180K miles on it. I recently had enough money to buy a new driveshaft so I went for it. Found a fellow on ebay that custom makes them with new U-joints and splines. I sent him my measurements, 41 inches from flange to flange, and he sent me a shaft that is less than 38 inches, and not enough play in the splines to safely use it. When I talked to him he accused me of not knowing how to measure things, he is wrong. Anyways, sent it back and haven't asked him to remake one yet, he was going to just add on the 3-4 inches to the one he sent and I didn't think that would be strong enough, welds and such. So, I found another source on ebay, their measurements claimed 38 inches from center of U-joint to u-joint and I figured that would be about 41 inches flange to flange, bought it, same deal, about 4 inches short, false advertising. So, now I realize that MOST fj80 land cruisers have a shorter driveshaft than mine. I don't know why but maybe it is because later models have a viscous coupler adding to the rear of the transfer case? Can anyone shed some light on this? Can I put a viscous coupler on the TC and driveshaft after market? That might help end the "clunk". Is there a part number for the proper length shaft so that I can buy one? I'd still like to have the new shaft for the new splines and u-joints which might be contributing to the clunk, but it seems I can't get the right length because 1991 was an odd year for shaft length. Thanks in advance, Bob in Michigan.
 
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Hi all, I've had a clunk for many years in my 1991 land cruiser, about 180K miles on it. I recently had enough money to buy a new driveshaft so I went for it. Found a fellow on ebay that custom makes them with new U-joints and splines. I sent him my measurements, 41 inches from flange to flange, and he sent me a shaft that is less than 38 inches, and not enough play in the splines to safely use it. When I talked to him he accused me of not knowing how to measure things, he is wrong. Anyways, sent it back and haven't asked him to remake one yet, he was going to just add on the 3-4 inches to the one he sent and I didn't think that would be strong enough, welds and such. So, I found another source on ebay, their measurements claimed 38 inches from center of U-joint to u-joint and I figured that would be about 41 inches flange to flange, bought it, same deal, about 4 inches short, false advertising. So, now I realize that MOST fj80 land cruisers have a shorter driveshaft than mine. I don't know why but maybe it is because later models have a viscous coupler adding to the rear of the transfer case? Can anyone shed some light on this? Can I put a viscous coupler on the TC and driveshaft after market? That might help end the "clunk". Is there a part number for the proper length shaft so that I can buy one? I'd still like to have the new shaft for the new splines and u-joints which might be contributing to the clunk, but it seems I can't get the right length because 1991 was an odd year for shaft length. Thanks in advance, Bob in Michigan.
Do you have any lift on the truck?

The 91-92 never had the VC, but IDK if it can be retrofitted. Most folks are waiting to get rid of it.

Maybe @jonheld can shed some light on DS differences with the 91.
 
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i have about 4" of lift and never needed a DC driveshaft. I recently changed out my damaged stock driveshaft due to damaged from rocks and i just bought another stock drive shaft and replaced all the U joints, works like a charm. If your cruiser is not lifted over 3", i would just replace the U joints and re grease.
 
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Do you have any lift on the truck?

The 91-92 never had the VC, but IDK if it can be retrofitted. Most folks are waiting to get rid of it.

Maybe @jonheld can shed some light on DS differences with the 91.
The FJ80 did not have a VC in the transfer case, so the rear output housing was shorter. That in turn made the rear driveshaft longer.
You can replace the transfer case with a later version, but I can't imagine doing that.
Make the radio louder.
 
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Thanks for the good advice Jon, you always come through. I'll look up on how to lock the CDL but to save time can you give me the steps? (there are lots of locks, buttons and levers available to me sitting in the drivers seat, and I'm not familiar with them all. Thanks, Bob.
 
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Push the button my dude.

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