it seems every site i go to has a different part number. my truck is srw f350 with a leveling kit only on 35's.
ive done lots of searches here as well but cant nail it down to whether i need 4600 or 5100.
I just put Bilsteins on my Excursion. They sell them by height.
They have:
0"-1" Lift (Stock Height)
2"-4" Lift
4"-6" Lift
Up To
10"-12" Lift
The difference between the 4600 and the 5100 is the finish only.
The 4600 is yellow with blue boots
The 5100 is Zinc Plated with Black boots. They stay nice looking longer. In my case with a stock height Excursion you can only see about the top 3" of the Blue Boot and the rears all you can see it the bottom inch or so since the fuel tank is behind the axle you can not really see the rear axle....