Ooops, forgot to come back and update this thread.
I had spent some time trying to locate another 3.92 rear end, and all I was finding was crazy high mileage units (nearly 200K), or $1,000+. Even the lower mileage ones were pretty expensive, $600+, but I couldn't find one in 3.92 locally. I figured by the time I bought one, had it shipped here, and had it regeared, I was going to be back in the expensive catagory again.
Ended up finding a yard that sold me a shaft for $125, and a brake/backing plate bracket for $50, so I took a chance. Put a new seal and bearing in with the shaft, and have put 5,000 miles on it since without an issue
I got REALLY lucky on the bracket, as every yard I called wouldn't sell it seperate from the rest of the axle. Except this one, because they thought I meant the same part you could get from any auto parts store (despite verifying it with them multiple times, lol), and when I got down to the yard they made it right. Major props to Reeve's Auto Wrecking in Phoenix
I couldn't get another backing plate from the junk yards, and I keep forgetting to call the dealers to see if it's available seperately, so I'm still without a parking brake, but at least the truck has been driveable