I have a 91-92 MJ NOS unit and 4637184 is the correct p/n from the parts manual. However the 4637184 is not stamped anywhere on the sending unit itself, only on the original Mopar box - if it has one. To verify for sure it's correct, the electrical harness should have the following tag:
I'll call them later today and see if they will verify. Nice find! These are the rarest of the rare MJ sending units.