Amerijet 737 at ELP
Amerijet also has a former-Southwest 737-200 sitting in the backlots over at El Paso as well. I asked a lineman what it was doing there, and he said that they had purchased the aircraft, and when they started getting it ready for the cargo biz, they realized it was going to end up costing them a boat load more money then they had anticipated - so it was just sitting there being unused.
Might be a similar story to the 727 mentioned above.