Ok guys, Need some help here. When to look at hopfully my next car, a 70 SS LS6. But, when checking the transmission number a got snagged.

Main Case casting # 3925661
Ext Housing casting # 3978764

Vertical number aft of the Main Case casting # R17A (this is all I can see)

Is this an M22 (C) as advertised? Or and M20 (A)

Didn't all LS6 cars come with the M22?

Thanks in advance!

Mine is a P0R27B. October 27 M21. My car is an L78 though.

The B indicates an M21
An A indicates an M20
A C would indicate an M22

Looks like yours is date coded October 17 and is an M20.
All LS6 cars came with an M22 or an M40 Turbo 400.

Ok guys, Need some help here. When to look at hopfully my next car, a 70 SS LS6. But, when checking the transmission number a got snagged.

Main Case casting # 3925661
Ext Housing casting # 3978764

Vertical number aft of the Main Case casting # R17A (this is all I can see)

Is this an M22 (C) as advertised? Or and M20 (A)

Didn't all LS6 cars come with the M22?

Thanks in advance!

Yes, all LS6 cars came with the M22 or T400 auto. There should be a couple of digits in front of the R17A. Like P0 or P1. The A does indicate it is an M20 wide ratio. C would be correct for M22.