My 2 Cents...
I just recently went through the infamous "Northern Rust" issues on my 93 RCSB 4x4.
I purchased the truck for $2K from an auction in Pennsylvania and shipped it to Houston without looking at it. I knew it was going to be bad....But it was worse than expected.
A complete frame swap was the only way to fix the under body and ensure the truck would be safe. The frame rails from the cab back looked like Swiss cheese.
Price and mileage were the 2 biggest factors leading me to make the "blind" purchase. (162K miles)
Complete frame from salvage yard was $500.00. I found it on line in Oklahoma. 8 hour drive each way...
The cab corners, rockers, lower door skins and all 4 fender arches also suffer from RUST. The frame swap took longer than expected simply because of issues mentioned above. Fasteners are worn away to the point that wrenches will not fit. Recycled components like the drive shaft and rear axle were all cleaned and stripped of all rust and coated with fresh paint.
Judging from the Photos, that truck is in exceptional condition compared to the truck I bought. LOL
In all honesty, I was prepared for a frame swap and had already sourced a replacement frame before the truck was delivered. I was prepared to do all the work needed and was actually expecting it to be cancer queen.( i was not disappointed)
Fast forward 2 months, and the truck is once again on the road with current safety inspection and registration complete with all new brakes and tires. This truck is and was always meant to be a weekend driver and an on going project. The fender arches, cab corners, doors and rockers will get repaired 1 piece at a time.
Now that I have told you what I have done, I will offer this advice...
These 4X4 trucks in Regular cab short box, V-8 are a rare find in Texas and as you mentioned, can be super expensive even with extremely high mileage. The same Regular cab short box, V-8 truck with a 5 speed manual trans is a freaking UNICORN in TEXAS!
I looked for a year and finally said screw it and bought one from up north where they seem to be abundant. The issue is that all of the "northern" trucks are plagued with cancer.
If you find one, consider buying it and selling it to me.
The truck looks rough from the under side but a lot less than I would expect from a plow. It appears to have all of the normal rust issues associated with a northern truck. The roof is also a particular area prone to rust as well as around the front and rear window frames. There are better trucks available. If you are willing to wait, and even travel some to go get one, I suggest you pass on this one and continue looking more locally or within 300-500 miles. If you have the mechanical skills, the tools and the time, travel and go inspect the truck to see its "real" condition. Anything and everything about this truck can be repaired or replaced. (even the frame) It just depends on how much you are willing to undertake and how much you want to invest. The frame is the biggest issue to worry about, replacements can be found, but they are somewhat difficult to locate.
If you truly think this is "THE TRUCK" and are willing to make any repair needed, purchase the truck and know that you will find plenty of support and encouragement on this site!
Good luck and let us know how it goes.
If you buy it, bring it to Houston and I will help you fix it up!