[1990Z51]

Here is a description of how to replace the front differential bushing with an Energy Suspension 3.2125R 1-3/4" OD Rear Frame Shackle for Chevy Truck. Cost is about $20 (amazon). This is very easy and the fit is great. The only drawback it removing the exhaust if you live in the rust-belt

This was described here without pics http://www.cadillacforums.com/forum...82041-differential-bushing-16-diy-option.html

... so here is a version with pics!!

Take off the exhaust

Remove two rear differential bushing bolts. The bolts do not come all the way out and they do NOT need to.

Remove the front bolt and nut (be careful, you need to support the differential with a jack stand) The differential will drop down enough to service the front bushing

This is what came out of the front bushing (the outer cage stays in place - no need to try and press it out)

 

[1990Z51]

Next you need to cut the new bushing down so it is 2.5" overall in length. I took 1/2" off one of the halves to get the correct length.

You also need to cut the center insert down as well.

 

[1990Z51]

Then you just place the bushing in and bolt everything back together!