Most likely, it'll be a Timken model 221. It could also be a Rockwell, they are very similar. I'm not 100% sure where to tell you to look on the T-case to find the ID, but usually they either have a tag or casting mark on the case between the input/output shafts.
A picture might help, I'll look in my manuals some more and see if I can find out some more info.


Bill Burmeister