Bimdapogs wrote:I've no idea which is which.
Then it won't matter which you get, will it?
The originals all use slot car brushes (vintage 36D) which are almost impossible to find, so running them is almost suicide for such a collectible. These motors were all designed to run on 7-cells, too, so with today's electronics, they aren't really useful for anything but beautiful shelf queens. They are such rare and valuable motors, running them in a car should be forbidden, anyway.

I wouldn't necessarily worry about which is which unless you are looking to re-sell them. Take the cleanest ones he has and run.
All Checkpoints are wicked motors, but stick with the machined endbell versions with the steel cans and wet magnets (so not #2). The best motors Big Jim ever made were the wet mag Platinum II with the machined endbell and the .063" thick steel can.
I have a case of them, some without decals on them, and that collection is fantastic. If it were me picking from that lot, I would take #1 and #4 from the left. #4 is the gem in that group, IMO.
Good luck, that's a rare and wonderful find. You're very lucky to have the opportunity to find those and buy a couple. Most people will never even ever get to buy one, let alone see one in person.
-doug