I was told that one or two years it was on the right hand side (passenger), which made the cable shorter. Then it was moved to the driver side, which made the cable go diagonally across the car.
In my opinion, I do not need a navigator/co-pilot in my GTV unless I am on a rallye ... Hence I consider the driver (left hand size) to be more customer-friendly. Of course, I am ingoring the opinion of alfistas in right-hand drive countries.
Well, here's one that makes no sense from LHD or RHD perspectives. My 69 USA gtv 1750 series 1 has the lever for allowing the backs of the front seats to be folded forward located on the inner sides of the seat backs (furthest from the doors). Originally I thought the PO had rotated the seats, perhaps to even out wear, but have since seen several other cars with the same configuration.
Thanks for the enthusiastic discussion here! My '71 had it on the pass. side, so I was programmed to find one there too on the '67. The '67 was sold in Rome, LHD, and brought into the U.S. - latch on passenger side. Better than no latch at all!