third member

so i know the toyota rear ends are pretty universal, what about the third members? Are the 79-95 third members all the same and interchangeable?

Not really. There are two different axles sizes, 7.5" and 8" which have a different bolt pattern. There are also 1 ton units that have a larger spline count.

how can i tell which is which, guy has a 79 thirdmember i would like to use on my 93 rear end..

measure the ring gear, count the splines on the axles and check the third member bolt patterns to each other.

You can tell an 8" from a 7.5" differential or housing at a glance. The 8" has (if looking at the pinion flange, or front of housing) a stud that is sightly to the left of 12 O'clock. It also has two longer studs. The 7.5", I believe the highest stud is right at 12 Oclock and has only one long stud.