You'll have to be more specific about what you want in order to receive good advice. You could have lots of shops "repair" it or even "rebuild" it but how good are they? You could possibly buy a reman from a Dodge dealer. You might be able to find a salvage yard takeout but I"d guess chances are slim.
My advice is take the truck to a shop who will pull the transmission and strap it to a pallet and ship it to Standard Transmission in Fort Worth, TX or Blumenthals in OKC. Both of these companies are the premier rebuilders for NV-5600 and other manual transmissions. Both are TDR advertisers and are well known to TDR members. Standard rebuilt an NV-5600 for me several years ago. I enthusiastically recommend them.
Have it professionally rebuilt, have the shop install a new clutch assembly and related parts, reinstall the tranmission, and you'll have a reliable and long lasting rebuilt transmission.
It is a complex transmission and parts are hard to find. The transmission weighs approximately 360 lbs. so it is not a job for an amateur.