An interface from HPIL to HPIB (GPIB) did exist for these and low cost calculators and controllers:
HP 82169A hpil to gpib converter. - source Wikipedia.
I have at least one - but I am keeping it for my HP 71B and HP 41CX calculators. There were also some 2225 printers with the HPIL interface, on these, if the interface was parallel then you could convert between GPIB and Centronics parallel by changing the IO port and card, if it was HPIL then you could convert between that and RS232 by changing the IO port and card.
Our retired 3468A design engineer may be able to shed some further light on whether you could do the same on the DMM. The parts or assembly might be available on eBay or from a salvage unit, or from the HP computer forums. I also know that there are HP collectors for the small calculators and controllers - years ago I sold a couple of boxes of the cables adapters and controllers for ridiculous money, hundreds of dollars.
Don Bitters
