Posted below are a couple of pics of a shifter assembly that I got a number of years ago for what I believed was for a Cadillac Hydromatic! A freind of mine was interested in the shifter an checked it out for his Hydro out of a 56 Olds but said it would not fit even closely! Are the cases that much different from an Olds to a Caddy? I wouldn't think so! I would like to figure this out so at least I know what I have!
It looks like one of the "universal" automatic floor shifters that I used to sell when I worked in an aftermarket parts store/speed shop.
The Jalopy Journal
