Broken parts in core C6 trans

Disassembled a parts trans and fount this inside:

In the first picture you can see the groove that was ground into the side by some previous rebuilder.

Also found out the case had been grappled on both sides, probably from a junkyard, and I'm considering the case is now junk too.

Better take a good look at the lube return . Not common for a failure like that ,
Also what you refer to as grooves ground by a previous builder are factory
What does the rest look like ?

The rest of the internals were very clean and the steels and clutches looked close to new.

Reused the case as a dummy trans for fitment.