$3800 is on the steep side for an extended cab F250. It better have some redeeming quality like receipts for a new injection system, new clutch, tires ect. The clutch is 6 beans, that brings us to $3200. I'd be holding out for a crew cab at that price.
To be honest, these rigs can seem like a nightmare, getting them back into shape after 20+ years of use and abuse. The thing is, once you get them back into shape. the dollars per mile far exceeds ANY newer truck. A 30 some thousand dollar '08 Ford, Chevy or Dodge will not net you a more reliable vehicle, just way more costly repairs when something goes wrong.
A fresh fuel system and a good turbo should make towing acceptable. I grossed 16,000lbs and was happy with my performance towing from Jersey to Michigan and back last year. Fast? Not really but I held my own. I'd drive to Kali in an instant at this point knowing my truck is reliable.
I have been left stranded only once, had a 2" crack in a cylinder wall, gulped antifreeze, hydro locked occasionally, but still got me around for WEEKS before I called it quits and yanked the engine. Any one little tid bit goes south on a newer truck, chances are, a wrecker is being called. I have seen 2012 F550's with the Ford/Mexican diesel in it broke and in the shop with repairs that total in the THOUSANDS, with less than 45,000 miles on them. $60,000 for a truck and you have to bank on the warranty, no thanks.
For less than $20,000, you can go through an IDI inside and out, and have a truck that will flat out be more reliable than anything new. I will take the "lack of power" that goes with that.