Here is a tip from old school docs I have and quoting:
"Pull the front bearing retaining collar off of the front of your Top Loader. If you see a machine mark on the input shaft, it should be a wide ratio transmission."
I have seen them and it looks like they just turned a groove in them to ID the trans, but that was a long time ago.
You may want to just call Dave Kee. He will help you.
Good luck!
