I have a 1991 4wd f250 and have a broken spring in the rear. I found a set of f350 4wd springs but they are from an 86. They only want $200 for all 4 sets of springs. Question is, will 86 springs work on my 91? What about the front springs, are the heavier than the f250 springs?

 

Rear springs should be the same, maybe an extra overload. As far as the front springs, while they will physically bolt in, no you should not use them. The solid axle springs are lighter than the TTB springs and it will not sit /ride correctly. Keep them around if you plan to D60 swap, or sell em to someone like me who is collecting parts for one.

 

Thanks for the help! I would eventually like to do the solid axle swap on my front end. I haven't figured out yet exactly what gearing I have, but I'm pretty happy with it. That truck usually runs about 2100 rpm at 65 miles an hour. What gearing options are available with the D 60?

 

Sound like you have 3.55 gears, if you are running the stock 235/85/16 tires, depending on what tranny you have. The D60 came from the Ford factory with either 3.55 or 4.10 gearing. Aftermarket, there is a wide range of gearing available.
On the springs, they will work on the rear, but count the leaves. Some had 4, some had 5. It is best not to mix them, ie 4 leaves on one side 5 leaves on the other.

 

Well, I figured out that I have 4.10 gearing. I was able to find the tag on the axle, and the dealer confirmed it with my vin. What gets me is after checking my MPG over a few weeks, I'm only getting about 13 MPG when I drive between 55-65 MPH.