1964 Warn Overdrive
Here is a nice Warn Overdrive booklet.
Two model was available; one with 26 tooth and the other one’s with 29 tooth. Everything from CJ-3A and earlier should use the 26 tooth. From the CJ5, it should be 29 tooth. So if you own a CJ-3B or a 475 (Wagon and pickup) then you must need to check what you have.