Any transmission experts?

[will2k2]

I've been working on the Th350 in my newly acquired $400 Cheyenne trying to work some bugs out.

First off, I know this trans is not long for this world. It's lazy going into gear, and it's not the orginal- the truck is coded for an M40 TH400.

I pulled the pan to fix the extreme slop in the shifter after I determined that it was internal to the trans. The nut securing the manual lever together had backed off-quick fix.

However, upon inspection of the pan I found something that is very likely related to and the cause of my quirky 2-3 shifts. When the trans is cold its shifts fine. After it warms however, it refuses to shift from 2nd to 3rd, unless you shift the lever to 2 and then back to D..then it shifts right away.

What I found in the pan was several fragments of what looked to be a thin snap ring or something related. Looking along it's surface you can see machined diagonal grooves..I'm not familiar with transmission parts so i don't know what it is.Any ideas?

Thanks!