Is there any way to tell if a transmission has been rebuilt?

[Hawaii-50]

In a nutshell, my brother had the AT transmission in his 93 Camaro rebuilt, and I'm a bit skeptical b/c he had a driveshaft problem the next day with symptoms that were exactly the same as what AAMCO said required the tranny to be rebuilt. I'm thinking it was the driveshaft all along. Are there any obvious things to look at/for? Any help appreciated.

 

[4valvemach]

You could
look for new gaskets on the transmission pan
check the transmission lines to see if they have been removed
pull the pan and see if it has a new filter
:shrug:

I would think you would have to pull it apart to really tell if its been rebuilt