[Vwdiesel] 1.5 or 1.6 pistons?

[Bart Wineland]

   I contacted a fellow that is selling some VW diesel parts on e-bay
looking for a single piston for my '89 na original engine I am hoping to
put back together. When I bought the car the engine was shot and it turned
one of the pre-combustion plugs came out of its place at some time and
hammered itself into the top of the piston and egg shaped the original seat
it came out of so badly it trashed the head.   I have since found what I
think to be a good replacement hydraulic head but need one piston and
rod.  This fellow says he has a full set he is willing to sell  very
reasonably but doesn't know if they came from a 1.5 or 1.6.  Actually I am
wondering if they are possibly the same and the engines were just stroked
differently or do I need to pull one of mine to get some measurements to
compare to his?

Thanks much,

Bart