I was able to pick up a nice 53310A including Option 31 (2.5GHz Channel C). Also found a second 53310A that was listed as having some display problems for cheap but it included Option 10 (HP 10811 OCXO). The entire back panel assembly is Option 10, just swapped them around and now I have a fully functional unit with Option 10 and 31. Also have 4x CY7C194-25PC CY7C194 64K x 4 Static RAM's coming so I can give it option 01, thanks TurboTom for the info above!
Option 10 OCXO and linear power supply which always runs;
The 10811 OCXO;
Only had a few min here and there to play with it, but found some interesting things regarding my 10MHz references.
HP 53132A with High Stability OCXO (HP Option 10);
BG7TBL GPSDO with UCT 108663 OCXO;
BG7TBL 10MHz Distribution Amp with UCT 108663 OCXO;
Siglent AWG reference out;
BG7TBL Distribution Amp with GPSDO feeding;
So the cleanest signal appears to be from the BG7TBL distribution amp when being fed from the GPSDO, followed by the distribution amp running on its internal UCT 108663 OCXO, then GPSDO direct, then the HP 53132A's 10811 OCXO out, then the Siglent AWG reference out. Interesting that the distribution amp seems to clean up the GPSDO some. Anyway, this is far from scientific, just me fooling around. I have lots to read and lean about this instrument and how to use it properly.