I think the front shocks on a 2wd mount differently than a 4x4 because you have springs up front and I have torsion bars. As for the rear it should be the same. I just searched a little online and could not find a 5100 series front shock for a 2wd. but did find a 4600 series for the front.
I know the hd's are too stiff for dd'ing. Should I run the same shock all the way around or could I run 5100 in back and 4600 in front? Is there much of a difference between them?