help identify this transmission. Supposed to be A518

It's nearly impossible to tell just by looking at the converter but the input shaft tells the story all by itself and it is as JAS0162 described. He is also correct on them being used on the late 360 LA's. I had a 1990 model that was a non lockup version but most are lockup units.

Here's a picture of a set of input shafts showing the difference. The top picture is a lockup input shaft. Bottom is non lockup