I have a seal kit for the late 1g pump which is the two piece. I bought it not knowing it was different from the seal kit for the '90 pump which is a three piece. To see the difference between the two, check out these links:
I believe the '90 3 piece kit is p/n mb501695, and the '91+ 2 piece p/n is mr244546, but double check w/ a dealer or JNZ to be sure. I have a 91+ 2 piece seal kit that I can sell you if that's what you need. There are obvious visual differences in the seal kits. If you take apart your pump you will be able to clearly distinguish which kit you need.
Here's a pic of the '90 3 piece seal kit (missing a few o rings that I had already installed on the connector):
Here's a pic of the '91+ 2 piece seal kit:
