Ball Joints/Axle size

[eternalcombustion]

I have a d250 diesel dually. I'm trying to replace the articulating joints on the front end of my truck. I want to start with ball joints. Rock auto has quiet the selection. And so much so that I'm not certain as to what I have. Instead of using wording like 2wd dually, or 4wd single narrow body or anything that makes obvious sense to me is avoided in favor of a 3000, 3300, 3800 and 4000lb axle designations. Does anyone know what these correspond to?

[Mark Nixon]

They correspond to the front axle weight rating.
This is found on the door sticker under "GAWR FRONT" on the door tag.
ALL Cummins 2WD trucks are 4,000 pound front GAWR, be they 3/4 ton or 1 ton.

Mark.

[eternalcombustion]

thanks, that totally resolves my issues there