Is there a rear out there that will slap right into my 85 trans am without an problems?? It has to be a posi unit I heard of a S10 pickup but I'm not sure! I need a rear fast I dont have time to really get into all the work. I will do exactly what you said alex with the my t/a's rear when i get it out! thanks makes alot of sense! PLEASE HELP!!!!!!!

 

You need a rear axle assembly with a "torque arm" attachment system.... that limits your choices. And, your 3rd Gen rear axle is about 3" narrower than the 4th Gen axles, so that limits it even more.

You might want to think about posting your question on "3rd Gen Tech", where you are more likely to get a correct answer, rather than here on "LT1 Tech"......