3500 Gas DRW Front Axle Weight Rating

[RKCRLR]

I have a Big Horn gas 3500 DRW on the way. The build sheet lists "6,000# FRONT AXLE W/HUB EXT" but from what I've read the FGAW will be derated to 5,500 lbs with the gas engine. Does anyone know exactly why the front axle is derated? I'm assuming softer springs are put in for the gas engine. Does the derating come from the reduced distance to the front bump stops when loaded? The weight distribution being different when a truck is loaded vs the diesel engine in the front? Or something else?

Just curious as I will probably never bump up against the 5,500 FGAW limit.

 

[Darkside]

Curious about that myself, my 2500 Hemi is the same way, 6000 lb on the build sheet, but only 5500 lb on the door tag…