Which drive shaft should I be using?

[NateDogg024]

I'm using the drive train from my 93 GMC K2500 6.5LTD w/ NV4500(working on confirming that trans) to put into the donor truck that I got. The donor truck was a 90 Chevy K1500 z71 had a 5.7L V8 gas auto trans 4x4.

I was very happy because the trans cross member didn't need to be modded at all the 93 diesel/trans dropped in perfectly, but which drive shaft should I be using? The z71 drive shaft was about .125 - .25 inch longer, and in much better shape cosmetically. The diesels drive shaft is very rusty. Other than the rust, they are both in good shape no dents and both drove fine before deconstruction.

Now this is why I ask which one should I be using. The z71 drive shaft is a smaller overall diameter. (sorry i don't have the measurements with me) and the diesels is larger in diameter. Could this just be a difference between a 1500 and a 2500 drive shaft or is it a torque related difference. I should also mention that the 93 was originally mated with a 14 bolt rear end w/3:43 gears, but now ill be using the 10 bolt from the z71 w/3:73 gears. (I could be wrong about the gearing its been awhile)

I would prefer to use the z71 drive shaft not only because that is what I currently installed but because it's also less rusty. I don't want to twist the drive shaft and brake something. That's happened to a friends truck and he broke his tail shaft housing, which didn't turn out good.

Thanks for reading.

 

[THEFERMANATOR]

Chances are the diesel shaft will be a thicker walled shaft. Many of the gasser shafts were only .040 thick tubing whereas the diesels got .062 for the most part. Diameter is mostly a function of keeping the driveshaft from pretzeling at high RPM's from critical speed vibrations. The larger the diameter, the more RPM's it can take without pretzeling with both shafts being the same length. Another thing of note is most all diesel shafts used a 1350 u-joint whereas the gassers for the most part used 1330's or there 3R setup with internal snap rings. Personally I would go with the diesel shaft, and swap the 14 bolt in as it is ALOT stronger than a 10 bolt.