How can I tell if an auto trans is a 400 turbo trtans? I ask because I think I found one in the local yard I go to. It's a 2500 truck with a carbed 350 motor. I think it was an 83 model. The tranny pan is rectangle in shape with no cut corners. I only mention the corners because there is another chevy truck that has an auto and the tranny pan has a small 45 degree corner on one end of the tranny pan.

This same truck has the 8 lug set up with a low pinion front axle. Not sure if that helps with anything or not.

Rectangle in shape no cut corners--probably a 700, square with a single cut corner in the rear of the pan 350. 400 is kinda square and oblong at the same time--been described sometimes like the shape of texas

TH400 pan gasket:

http://www.novak-adapt.com/images/graphics/th400_specs.gif

It's not a 400 then. It must be a 700. Is it worth grabbing? if I don't grab it then it will get crushed. I hate to see good parts get crushed.

sounds like a 700R4 to me. Basically a 4L60. Might be worth keeping if the price is right. They have a really deep 1st gear 3.06:1, I think it is the deepest 1st gear of all the GM auto trannies.
That tranny came in 82-92 3/4 and 1 ton trucks/vans and probably in Vetts and Cameros too but dont quote me on that, I dont know much about cars.

I didn't have time Saturday to pull it but i will next Saturday when I get back to the yard. I will even snag the 8 lug LP front axle. thanks