MBDoc pretty much nailed it, sometimes the front clutches will wear to the point where the apply piston will hit the drum. This causes the thing to click and clank loudly in reverse. The front apply piston will leak as well causing slow engagment. Low working pressure and sticking valvebodys (also very common, esp. cold) will cause this as well. Personally, as I've found it cheaper to fix worn parts than fried parts, I'd look into a overhaul rather than letting it fry. (hard parts aren't cheap)
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.