Fly wheel starter ring.

They maybe the same, I will check my 63 parts catalog and see.

In the 63 catalog they are the same for flywheel or torque converter they do list 2 different ones, but I suspect that is for gear reduction starter or non-gear reduction starter. 2121196 w/o the letter R and 2121195 with the letter R, I believe with the letter R identifies as a gear reduction starter. The non reduction starter was an early use and may have been continued in Canada later than the US.