tranny issues 1996 F250 4x4

Hi all, just found this page & signed up. My 1996 F-250 decided to burn up it's tranny yesterday on the way out of the Sierra high-country with 2 horses in a heavy old Miley behind it. It's a 4x4 Auto w/ OD. At least it *had* OD. There are bits of clutch material in the tranny fluid, I have no reverse, it'll go down the road in drive but only shifts from 1st to 2nd & gets stuck. Can't put it in 1st or 2nd manually though, just acts like it's in neutral. Pretty sure I need to either replace or rebuild. I've talked to a few respected locals about the best options for fixing the truck but I'd like to see if there's anyone else out there with good ideas. The truck has almost 122k miles on it, the 460 engine runs great, & the brakes are brand new (as of last Friday). Do I rebuild the old tranny, adding clutch plates, HD cooler, etc to make it a HD tranny, or should I just go stock & hope for the best in the mountains from now on? Most of my hauling is up in steep terrain. Should I just find a used tranny pray to the car gods that it survives as long as the engine will? I will most likely be keeping the truck for a few years as it's not paid off yet. Thanks for your help!

If you plan to keep the truck, have the tranie rebuilt, and a cooler added on, especially if you are towing a heavy load. A new tranie may cost a bundle, shop around.