TH350 Hunk's of metal in "Rebuilt" Transmission

[rball716]

Hey guys I'm trying to identify what these chunks of metal are from that I found when I pulled my transmission pan to change the filter and put in new fluid in my newly purchased transmission. It was supposedly rebuilt 5,000 miles ago along with the engine. Just wanting to know what I'm walking into if I attempt to rebuild it whether I'll just need a normal rebuild kit or more. I have this trans as well as the original 700R4 that I don't think has been touched before and If I need a full rebuild which would you recommend to do. Engine is a 383 putting out around 430 hp. Thanks, hopefully someone can help out.