Our current truck is an '85 F-250 4WD w/460 regular cab. My wife keeps wishing it were at least an extended cab, so I'm shopping.

This is my criteria:
F-250 or F-350
Extend cab or crew cab
8' bed (or wheelbase to let me install one)
4WD
Diesel
Manual transmission (will accept automatic if it's a good deal)

Given the above, are there any specific years I should look for, or avoid?
Any specific engine to hold out for, or avoid? I'm aware of the cavitation issues of the 7.3 and some ways I can check for pin holes.

Thanks.