On the 722.1 tranny (you got the numbers right)in the 76, one must remove the hollow bolt attaching the dip stick tube to the pan in order to remove the pan. This acts as a drain plug to a certain extent. With the dip stick removed pull the other 4 bolts and remove the pan. Replace the filter and the pan gasket. Drain the torque convertor also.
Dextron III is suitable for also MB trannies till the 722.6.
BTW the big plug with the half moon relief is the secondary pump. Removing it won't drain much fluid, if any.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
[This message has been edited by stevebfl (edited 09-04-2000).]