We used to use M-80's to get the rabbit out of the hole

Maybe you have just posted the problem with the 2101s.
The 2101s should have the number 1121.
The 2100s should have the number 1127.
The 788 base is from a much earlier carburetor.
LOTS of folks out there that seem to think they can switch throttle bodies indiscriminately, as indicated by you receiving one with even the wrong size base, and having another with the wrong throttle body. Generally, the results of the switch are much less than desirable. The Carter engineers did NOT make all the different parts simply to shaft the stockholders out of a higher dividend. Engineers really do things for a reason.
Maybe now you know why you are getting "great deals".

Jon.