Might not even be automotive. Seller on a local for-sale site has no idea. If three small ones in a box are enough to do the job why not three big ones in a box. Who knows. See the two little built in wheels along the one side which seem to slide the blocks on the other side or maybe both sides. Looks like they slide out/longer.
Go/No Go gauges for internal broached key ways. Not a for sure thing but would work when production broaching keyways.
The Jalopy Journal
