There is a way to id....if you can decode the numbers on the sticker on the side of the trans... Somehow i want to say there is a z in the code. All ls trans have the center top bolt hole in the bellhousing.. And at some point the 4.3s got it too....

 

That's assuming no one has been inside of it or that the case has not been changed. A lot of theses truck are well past the 100k at this point in there life.

 

True.....

 

I was also told on the tag on the side if there is a z on it it is the 4l65e. Is that not true?

 

That's also assuming no one has been inside it.