Ah mei (bavarian oh my god ), this guy with 34401A in Bag is called peter. I am not sure, are you with old fluke 10v reference ?
a good news, i got few useable pictures from a youtuber with HP 3450B.
But this card has difference to avaible 3450B schematic. (Photo shows logic array is Signetics-TTL, schematic tells DTL)
1820-0094 & 0096 is old DTL and 1820-0303 and 0320 is Signetics TTL. Pinout vs S-TTL and DTL: just mirrored.
Despite difference logic IC: Fog about edge connector goes slow away . I have written youtuber, i need yet photo of bottom PCB. (yet unkown about timing signal on rear/bottom edge connector.)
Greetings
Matt