Muncie 4-speed identification

[DWC]

The 68 Camaro I recently bought has a Muncie that the seller said was an M21.
After looking at the casting numbers, I believe it may be an M22. The casting numbers are 3857584GM, P8S06, 3925660, 3088336. From what I've read, it's a close ratio M22. Can anyone confirm this?

Thanks,

Daniel