How can I tell if my D250 is over or under the 4000lb part difference?
Cab says gvwr 4670

 

What are you talking about?

 

GVWR is weight of the truck and load. No way it can be that light. maybe axle weight, but not vehicle.

 

When I tried to get ball joints for my truck they asked if it was over 4000lb or under, I assumed over, and when I got my ball joints, they where way to large. So I returned them and got the under 4000lb and they where the same.
But now when I ordered axle seals, I said under and it turns out I needed over. So what is my truck?

 

So even if that is axle weight, why are replacement parts all under 4000lb listings

 

There is a front axle weight rating and one for the rear axle also. .They won't be the same for front and rear.

 

so where do I find this info?
what does the over 4000lb front end look like? Is it a solid axle or independent front end?

 

It can be a solid axle or independent front end. It is still given as axle weight.

 

so is that the difference, over 4000 is a solid axle and under is independant?

 

Not necessarily. All according to springs, frame, and all components of the suspension.