Thanks Guys,
I downloaded all your suggestions and will see if I can get them to work. In the meantime, I ran the offending mdl through MDL Repair and that seems to have fixed the problem with the planes not showing.
I still need to find a good, flyable Korean War B-29 as the planes in the Korean Combat Pilot addon are a bit rough and simple. In fact, I need to change most of the planes out for something a bit newer and more refined.
Thanks again,
Geary