Replacing rear driveshaft

[78 GMC Jimmy]

So I am in the process of replacing my rear driveshaft. It not in good condition and should be replaced. It has slowly made its way to the top of the priority list.

Pricing that I was quoted locally:

Re-tube: $500
Custom made: $500+
Brand new: $500+

Ya.... I'm not going to do that. I won't pay $40 for a candy bar either.


So I tried eBay, Amazon, FB Marketplace, Craigslist, Google, etc. No luck.

So I called around to the local junk yards and they all said they cant help, since the driveshaft is not a stock vehicle part because the rig is lifted with other non-OEM parts, such as the rear end.

OK, so I called around and found a junk yard that has 300 drive shafts on the self, with no inventory or other info. Just piles and piles of driveshafts.

I looked through them and found two that match my minimum and maximum lengths, had U-joints on either end, and a splined slip in the center - like mine does.

I think they are marked "Toyota". Visually, the U-joins appear to be the same size, except they are center clip'ed rather then having a clip on the outer edge. The ends of the replacement drive shafts have "caps" on the end that would would bolt onto the vehicle, rather than using straps that would hold the drive shaft to the vehicle. I plan to lose those end caps and just use the straps to hold the U-joint in place, like my original one is installed.

I have not tried to install either one yet, but today will be the first attempt. I will need to modify the rear U-joint, since mine is odd. The caps on the drive shaft are normal size, but the caps that go on the rear diff are bigger. Not sure why or what part number that would be.

I may need to swap some caps around between inner and outer clip style etc.

The new drive shafts are very heavy compared to my old one. Its like comparing an aluminum soda can to a steel water pipe.


Any idea what part number the be on the U-joint that has two different size caps?

Can you make a U-joint that was designed to be outer clip, become an inner clip by swapping caps?

Does the splined slip end go forward or to the rear of the drive shaft? Doesn't matter?


Any info or tips would be welcome.

 

[78 GMC Jimmy]

SUCCESS!!

2002 Toyota Tundra rear drive shaft - meet 1978 K5 Blazer!

The collapsed and extended lengths were correct, and it has U-joins at either end, with a spline slip in the middle.

The Tundra drive shaft had a CV at one end that I needed to knock off, along with some grinding. I needed to use the K5 rear U-joint, and custom build a U-joint for the front using Tundra bearing caps on the shaft and K5 bearing caps on the T-case, with two small spacers, but it works! I just drove it around a bit with speeds up to 60, and its perfect. The old drive shaft was bent and had bad vibration above 50, and this new drive shaft does not. It runs smooth at 60. After racing the rig around a bunch, the U-joints are cool to the touch, and there is no free play or other issues. Its fixed.

Drive shaft cost: $22 after tax (junk yard)

Labor: 3 hours.

Tools: Grinder, hammer, needle nose pliers, flat head screw driver, grease gun, wrenches, sockets.


I am definitely building my own drive shafts from now on.

Or more accurately repurposing and modifying drive shafts to meet the need. Way more fun, and WAY cheaper.