Driveshaft Troubles

I have a 1990 Ram 50 2.4l auto RWD. (My truck is an extended cab so it has a two part driveshaft) and ive been having a vibration issue. I have replaced the center support bearing and all the U-joints. This made the issue a ton better due to a destroyed center support bearing. But still the issue is still there. I raised the truck and spun the driveshaft to look for anything wrong. I discovered a large dent on the rear shaft part on the driveshaft. This dent is big enough to where its unrepairable. I just don't know where to find a new or used replacement shaft. I only need the rearward shaft. Ive called all salvage yards within 150 miles and nobody has a extended cab MM or Ram 50. I don't have the money to get a new shaft made. Any help or info would be appreciated. The rear shaft roughly measures 37" 13/16'.
My other question is, Is the single cab driveshaft the same as the rearward shaft on the two piece driveshaft? Instead of having the transmission yoke on the single cab it connects to the smaller front shaft to account for the longer body of the extended cab?

Before you removed and disassembled the driveshaft, did you mark the U-joint yokes to preserve their original mating orientations for reassembly/reinstall? If not, your driveline may be out of balance. You might see if there's a driveline specialist shop in or near your town that can check/restore driveline balance.

I think the longbed used the same two-piece driveshaft as the macrocab -- i.e., the frame and driveline is the same for either long-wheelbase (LWB) variant. Try car-part.com to search salvage yards nationwide, and try various combos of model year ('87-96) and make/model (Dodge Ram 50 and Mitsubishi Mighty Max).