G20 1981 transmission fluid
 

Can somebody help me in identify the gasket part number that is needed to replace the transmission fluid and filter?
as I was not able to locate the vim I have the model which is CG21305.
thanks in advance

have you tried a parts website, like rockauto.com ?

I was looking at it it's very good by the way, but I'm not sure if the engine is 5.0 or 5.7

Their websites that can decode the vin. What is the 8th digit of the VIN?

I was able to locate the VIN it's 2GBEG25M5B4147496 from what I can see it's ( (LT9) ENGINE,350,V8 (GASOLINE)). will check in that site in order to see if I can locate the correct parts.
thanks!

any other site like rockauto.com ? I've found everything there so far.
thanks a lot for the help provided.

https://www.napaonline.com

Engine doesn't even matter here. It's either a TH400 or TH350. I'd bet on the 400. Lots of sites online to ID the transmission by the shape of the pan and number of bolts, but the 350 has a more or less square pan with an angled corner while the 400 has a rounded end and a bulge on one side. Rock Auto shows both. A filter and gasket for it is a filter and gasket for it.