F1 3 speed top loader

[rotorwrench]

I can't quite make out the numbers on that case but it looks like all the 1940 thru 48 side shifter cases. The side cover is Mercury but the arms look to be earlier Ford parts. The 49 thru early 51 Mercury cases were all squared off on the back where the tail shaft goes on. It might have been for one of the F1 side shift set ups but they are kind of rare. Most F1 commercials have top shift.