Yes, I am a fan of the older Ford diesel vehicles. I don’t argue with success. I drive a 2001 F-250 HD pick-up with extended cab and 8’ box. About three times a year I pull a trailer weighing 11,000 pounds for 150 miles each way. I am careful. I change the tranny fluid every 35 to 40,000 miles. Something else you should know about this trans is that when pulling a heavy load or a lighter one going up a long grade, you should get out of overdrive. The vehicle will pull the load, but the trans will get fire hot and will be slowly hurt.
As far a $$$ go, you have to look at the what you are getting for the cost. Just because a book says it is worth a certain amount doesn’t mean you should bail out. You have the vehicle. It will service your needs. It has the size, comfort and accessories you want. Yes, there will be repairs and maintenance. Maybe at or more than the book value but not your value for what you want it for. Even new vehicles have problems, that is why the manufacturer gives a warranty. Even with a trans you will invest less than what it is worth. Just my opinion. Follow the manuals maintenance schedule to the letter at least. Always use the right engine oil for this motor. Very important especially for cold weather starting and smooth operation. I will also add that when purchasing fuel, most brands do not meet the cetane rating standards (like octane in gas)required for this engine by Ford. Sad but true. The one that comes the closest is BP. Again, this is important in cold weather. I use a cetane boost addative at fill up at the recommended rate. $5.50 treats 100 gallons. This insures starting, power, mileage and injector cleanliness also. Diesel vehicles require more maintenance and it also costs more to do. However, with proper care they run almost forever. There is a reason diesels are used exclusively in mediem to big trucks and anything in the equipment line. More power and torque, good fuel economy for the work performed and longevity. Good luck with the transmission issue. Invest the time and find a good independant shop.