Isn't the "HD" differential the only difference besides gearing?
I'd still contact Dave and ask. He might be able to tell you what your problem is on your current one, and it might be fixable saving you a **** ton of time and labor.
~F~
Yeah that is the only diff. Oh and when you swap in the non hd trans you need a different axle for the differntial side.
01 gtp-big cam e85 dd 78dodge- guzzling fuel 05 cummins- rollin coal
SMGPFC Two Nipple General