That must've been it! My friend and I bought them used at a yard sale at the end of the airport from a couple who had worked at TWA - they were former TWQ machines. I don't think we ever opened them.
I have a 7300 and a 3B1 (7300 is single half-height hard drives, 3B1 is two HH or one full-height). One has a Combo Card (RAM and serial) and a Floppy Tape card, I can't remember what the other has, but cards have been pretty thin on the ground. A DOS-73 or network card would be extremely nice to have.
The emulator actually started life because I couldn't find a machine for sale at a price I could afford, but the manuals were on Bitsavers. Someone later sold me the 7300 and 3B1.
