Back again guys,One more question.I went to the BIG O tires website to look for tires for my 1990 F-250 4x4.When I put the truck info in it asks if it is a 4x4 or 4x4 with H.D front end??? How do you know if you have the H.D Front end?

 

The HD front end would be a D50, the other LD option was an 8 lug D44. If you have a full floating rear axle, you most likely have the D50. You can also look at your front hubs, if they completely fill the center circle of your wheels, then you have a D50. The D50 also has special ball joints that make your truck extra expensive to align. Seems weird they would want that info for tire shopping. I guess if you have the HD version, they will probably try to sell you the tires with a higher load rating.