Hi Dan.Try Northwest Transmission Parts in Ohio for the countershaft that you need for the Warner T-86
Their web address is
nwtparts.com/
IF the countershaft is chewed up, take a good look at the inside surface of the cluster gear where the needle bearings run. The cluster gear bore may be messed up, too. Be sure to get new needle bearings with the countershaft even if the ones you have look 'okay'.
I can't take credit for the lead. Frank Rice (ReBop) recommended them to me.
I sent this same message to you via email, but I don't trust our system at this writing.
Let us know how you make out.
Regards,