i'm gonna be lookin at two different T3 turbos that I might pick up, but I need them to be the bigger ones that came stock on some cars. I don't remember the different sizes they were made in, but I need some help.

First off, what sizes were made?

Second, How do I measure them to check?

I have a dial caliper, and can measure them, I just don't know how to measure them or what to go by.

 

They should have a stamp on the exhaust and compressor housing.

 

You'll need to remove the compressor housing (just remove six bolts) and use the dial caliper to measure the inducer, which is the smaller side of the compressor wheel. Then reference the Turbonetics website or catalog to see what trim T3 you have. You probably want to use the largest T3 you can get your hands on if you've decided to stick with a T3. That would be a 60 trim, which was used on the 2.3 liter Ford T Bird in the mid '80s and the single turbo 300zx from the same era.