Q&A: Changing rear end from 2001 Chevy K1500 to 1993 Chevy K1500

Q: I have a 1993 Chevrolet Z71 that the rear end housing broke on. I also have a rear end out of an 01 Chevy Z71 that is making severe noise. Is it possible to Frankenstein the two and put the 01 housing on my truck? -Dr. Frankenstein

A: Dr. Frankenstein, the answer to that is it is possible. Here is what you are going to have to do. You are going to have to make sure that the ring and pinion in the 01 housing is okay or else you will have to buy a new ring and pinion. As far as the other components in the two, they will work. Also, make sure that your front end is the same ratio as the rear or you will break your transfer case. Typically the 01 has 3:73 ratio and the 93 will have either 3:73, 3:42, or 3:08. You can determine this whenever you take the two housings a part and remove the ring and pinions. Look at the pinion gear and you will see a number engraved on it. 11X41, 12X41, 13X41 stamped on it. If it is 11X41, the formula to determine it is divide 41 by 11. You get 3.73. 41/12=3.42, 41/13=3.08. Once you determine that they are the same and you have a good ring and pinion for the new posilock unit, put the ring gear on the posilock.

You need a new crush collar for the pinion. You will put the pinion in first and make sure you have it seated well. Then you put the posilock in. Once you have it in place, turn the yoke and make sure it seats well. Replace your axles and c-clips that hold them in place then the diff cover. Fill the differential with 80-90 weight oil and it is best use a tube of the additive while you are at it. This helps keep the oil from breaking down as quick.

Now comes the fun part, you should've removed the housing from the truck already. This is done by disconnecting brake lines and the 4 U-bolts that secure it to the leaf springs. Now you need a hydraulic press or jack to spread the leaf springs. There is about 2"-3" of difference in the size of the housings as you probably have already determined from the size of the axles that you removed from both housings.

Put the new housing on and bolt it to the truck. Re-install your brake lines and you are almost all set. Last thing that you have to do, the 01 rear end has disc brakes and the 93 has drum brakes. You need to replace the master cylinder. This should be done with no modification needed. Once you have the new master cylider on, bleed your brakes, replace your wheels and you are now ready to drive.

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