Good luck.
We had a couple of flights on US Air 734s before they retired them and also a few on UAL 733s and one on a 735 before they went to the scrapper.
This generation of 737 is radidly leaving the fleets, although Southwest still has a small fleet of -500s and a significant number of active -300s in the US.
Grab a flight on one of these while you still can.