How to tell Z/28 IROC T/A 700r4 tranny?

I just came back from a salvage yard that is going to get me a 700r4 tranny out of an 88-92 Z/28 IROC T/A, but the guy wasn't too clear on the differences, so I am a little leary. How can I tell that I will be getting what I asked for when I pick it up? The archived topics only say they have the better servos and valve body, but not how to tell them apart. Thanks, Joe

From the exterior there really isn't any way to tell them apart. They all look the same. The gear ratios, valve body, etc was different, but even to the eye as far as I know these all look the same as well. Only way too tell is to get part numbers and research.
From personal experience the 700r4 has probs with overdrive. I went through 4 of them in my T/A before I traded it in, however, I think the shop that "rebuilt" it had a lot to do with that.

I believe that there was a flat rectangular casting with a couple bolt holes on the side of the tranny.
3rd generation Camaro's and Firebirds had a steel beam that connected from the differential, up to the side of the tranny.
700R4's out of other GM's (Caprices, wagons, etc.)didn't have the mounting pad casted into the side of the tranny that I recall.
Sarge

AHHH yes, I forgot about this. It's actually on the "tail" of the trans if I remember correctly. Just one bolt hole, the torque arm (I think that's what it is called) bolted to the back of the trans and to the differential as well. The trucks didn't have that.