so as we all know zr2 s10/blazers come with 31/10.5-15 on them. What is different in them and regular s10/blazers? Would the leaf springs have anything to do with fitting the bigger tires? If so would i be able to swap in a set of zr2 leaf springs into my 1st gen 92 blazer 4x4 and be able to fit the 31's in the back?

 

The difference is that the frame mounts are different. I think the leafs are the same between the two. You might be able to fit 31s on a 1st gen though. I had a 93 as a winter beater last winter and put my old 31s on it. They had around 50% tread and only rubbed a little in the front. They were fine in the back.

 

zr2's have a 2" factory lift.

 

2 inch factory lift? how is that achieved?

 

With different mounting brackets for the suspension. Which are welded on

 

There are a number of threads that detail the differences. A search or two should provide the pertinent information. Something like "zr2+differences" may be a place to start.