Manual Steering Box for 'M' body

I understand that this is a A body forum but I feel much more comfortable with the advice I get here than elsewhere. As the title says, I have a chance to get a cheap manual steering box from an A body (year 72 or 73) and was wondering if that box with fit my M body?

My intentions are to remove much weight from the pig as I can. Removing the pump and larger box will save me about 20 lbs I figure. Besides, I can use the exercise wrestling the steering wheel.

Best Regards