Yes and no. A ZR2 has a 4" wider and heavier duty 8.5" rearend. The ZR2's are all 3.73 gears. If your ZR5 (which btw is strictly an appearance package) has the GT4 3.73 optional gears you'll be OK. If it has the GU6 3.42 gears you'll have to swap in the ZR2's front differential as well and have your PCM reprogrammed so that you ABS continues to work and the speedo is correct. You might also have to change driveshafts since the 8.5 rear differential is slightly bigger resulting in the yoke being a bit closer to the trans. You primarily want to make sure the driveshaft's front yoke doesn't bottom out in the transfer case. If it does it'll split the case.
If you're engine is stock I'd recommend looking for another 7.5" rear end from a 4wd S10 98 up with the same gears. Lot less hassle. Wouldn't pay over $100 for one.