OK, I'm rebuilding a pump stamped 42 78, which I'm guessing is 42 week of 1978. Andrew was nice enough to send me a pic, and his Valve had two grooves for orings and was stamped 03 83, I guess the 3rd week of 1983.
This valve assy was from a '79 300TD, so there is apparently a change of the part somewhere.
I'm sure we can all guess why.....

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John