Well good luck with the HD's, same shock more or less just with a painted case. I wanted the 5100's because the Zinc finish should hold up better against corrosion that the paint. Like I said, the 5100's are for stock height trucks as well as lifted applications depending on part number. They are adjustable on some trucks like a GMT900 with coils but not on the GMT800 4X4's in my instance. The ones I have are the same length as my stockers by the way, I checked.

 

Same reason why I choose the 5100 over the HD, they're exactly the same lenght & share the same valving. Both fit on a stock height truck or on a TB crank lift. The 5100 look better too.

 

I've had stock fronts on since new; knockin on 100K mi. The rears are QA1s. Ironically I bought them cause I couldn't find a direct app. Bilstein to work w/. 2/4 drop, even tho the QA1s are more $. And yes, Bilsteins are what I really wanted, but the QA1s are a sweet piece. And I'd heard mixed reviews on the Edelbrick IAS, which has a direct 2/4 drop shock. Ranchos were for stk. or lifted crowd. So it was slim pickins.
Next yr., I'll likely get QA1s for front as they have some that'll work for me. Hopefully, 1 day, when my truck no longer sees winters, no more back & forth shock swaps (done to preserve the alum. bodies & finish)

I run Belltech S&P in winter then swap over to the better ones when weather & road salt is gone. I'd still like to find some Bilsteins compatable w/. 2/4 drop for winters, as I think the Belltech's are shot & have been for awhile. I read thru this thread hoping someone had Bilsteins on their 2WD GMT800

 

I believe the 5100's for stock applications cover 0-2" lifts. It should be longer for those who crank the T-Bars.

I'm very tempted by the 5160 remote reservoir versions. Living in the middle of nowhere (Labrador) means I've got lots of roads that can tear up most suspensions.