I have a 1975 K5 without its rear driveline. I have a chance to get a used one, the only thing is its out of a 1986 Blazer. My question is, can this swap be done without any modification? I would really appreciate all the help I can get with this one.

 

It can provided the gears are the same. Sad part is it will likely be a GM Corp 10 bolt axle under the 86 Blazer and your truck has a GM Corp 12 bolt so you will be settling for a lesser axle in terms of strength, but if you are not messing around too awful much with it, you should be good.

 

So it shouldn't matter about the transfer case?

 

The 10 bolt should have the same u-joint dimensions as the 12 bolt so that should not matter. The driveshaft should also be the same or very similar in length between the two diffs. The transfer case does not matter at all in this whole swap.

The only things that you need to determine is the gear ratio of the two rear ends (original & replacement), the u-joint dimensions (just measure the width and the cup diameters), and then measure spring center to spring center to make sure you do not have to relocate the spring perches (which you should not have to).

 

I have to agree with swartlkkeverything should bolt right in, I just put a rear in my 89 Blazer out of an 82 pickup that was a 12 bolt,the rear that was in my Blazer was a 10 bolt the only thing I had to change was the yolk on the rear. The 10 bolt has a wider u joint but changing the yolk should take care of that. Check it by taking a cap off thedriveshaft u joint and see if it fits into the yolk ok.They should both have 30 spline yolk as mine had. Thats my 2 cents so keep the shinny side and the dirty side down and have a good one.

 

Thank you for all your help. I have yet to find out the demensions on that driveshaft, but I will. I feel confident that it should be very easy. Thanks again.

 

Its me again. Well the deal for the '86 driveline fell through. I have another one lined up, but it is out of a '90. Is this going to fit just like the '86 or will there be some modifications needed? I would really appreciate the help.

 

The rear axle will be the same as the previous 86 axle you were attempting to purchase. Just make sure the gears are the same and throw it under!

 

Thanks. I was hoping that was the case.

 

Well I got that drive line and well, I think we misunderstood each other. It's too short. Plus it has the slide in yoke that goes in the transfer case.