Colby,
Congratulations on buying your first vehicle.
I used to have a 1986 F250 with the 6.9 and then I jumped up to the 2000 7.3 PSD so I can't really speak for the 1989 you are looking at.
In general, diesels are more expensive to maintain than a gas engine...sometimes quite a bit more.
How many miles does the F250 you are looking at have on it?
Does it have any performance modifications?
Oversize tires?
Do you know the previous owner?
Does the seller have any receipts to prove the work they have had done on it?
Do you have someone who can look at with you that has mechanical experience with these Ford diesels?
Some more knowledgable members should be responding soon.
