My old Samurai with Calmini SR kit. I later found the rear shock plates were mounted to the outside of the springs and limited rear flex, thanks to the PO.
ZR2's have an 8.5" rear ring gear. Where as "most" regular S10's have a 7.625" rear ring gear. So, yes the axles are different in size as well as width.
Some regular S series' came with 8.5" rear ring gears, for example my 2005 blazer with a manual trans. has the 8.5, but it is narrower than a Zed or the same width as a regular S series.
The front ring and pinion is the same size for Zeds and Non zeds but the CV's are different.
Okay, I swear, last post and then I will un-hijack. Why, on the regular S10's is the rear track width narrower than the front? What's the point? It looks stupid.