Possibly. I used to think that there was only one gear for the auto, but a couple came up on eBay recently.

I'd check the gear in your current gearbox against the one in your rebuild gearbox. The yellow gear is for the 4.10 and the green gear is for the 4.52. I saw a pale greenish-white gear listed for an auto tranny recently. There's a black gear in the M41 that is incompatible with the other types.

Confirm the gear ratio of your axle. There are at least three types. I think 4.10, 4.30, and 4.52. There's a rare 3.xx type as well. 4.52 is a lower gear type for 220s. I have 4.10 on my 4-speed 122, and my M41 1800 had a 4.30. Automatics are supposed to have 4.30s or 4.10s.

I now have an M41 paired with a 4.10 in my 68 daily driver and my mileage and odometer read approximately 5% lower than actual.