I'm looking at a 1989 F250 Xcab 8ft. box 4x2 Diesel. It has a C6 trans and it's a non-turbo. The current owner guesses the rear gear as 3.73 or 4.10. Can anyone please tell me what the tow rating for this truck would be with the available gears? I've looked everywhere, I've called a car dealer, and I even tried to pay for a service offered by an RV site all to no avail.

Any other advice on this truck would be much appreciated. I'm fairly knowledgable when it comes to F-series trucks, but I don't know anything about diesels. The truck has 124,000 miles, new glow plugs and timer(whatever that is).

 

Back then the trailer tow charts were in the owner's manual.

7.3 Diesel
4.10 gears....3.73 was special order only not a common option
Auto trans

Max GCVW 10k w/ trailer frontal area not exceeding base truck frontal area and a max trailer weight of 2000#'s (Your truck GVW could be 8800#)

Max GCVW 13k w/ trailer weight between 2-3.5k and a total frontal surface of the trailer less than 60sq.ft.

Max GCVW 17k w/ 6250# rear axle and trailer between 6-11.5k and a total frontal surface of the trailer less than 60sq.ft.

For altitude operation reduce GCVW by 2% for every 1000ft above sea level.

I know this all seems like numbers but you need to know the truck weight as you plan to tow before really getting any numbers of available trailer weights.

 

The truck weighs 5700lbs.

 

Does the door tag list the rear GAWR?

To find out what axle you have.....
The bottom line of the door jam Vin tag below where Axle is printed.
H5 is a 3800#-4.10
H9 is a 3800#-3.55
19 is a 3800#-3.55
B5 is a 5300#-4.10
B9 is a 5300#-3.55
25 is a 5300#-4.10
35 is a 6250#-4.10

Unless you have an axle code 35 you have about 3k of trailer capacity.
If you have the 6250# axle you can tow 11.5k minus truck weight