... to change rear discs from iron to PBR's?

I assume you mean calipers. The swap is straightforward:

https://www.thirdgen.org/forums/faq-...iscs-89-a.html

Providing the year and make of the car in question is always helpful. For example, if you have a 92 TA with rear discs, you already have PBR's.

JamesC

No. I found a pretty good deal on a nicely freshened up 10 bolt, (Torsen posi, moser 28 spline axles, T/A girdle, yada, yada, yada), but it's got iron calipers. Sounds like a pretty straightforward swap. Thanks!