Hi Cannon -- We have a few folks who will be able to answer the duallie hub question for you. In the meantime, Recount the number of bolts holding your rear differential cover on -- you should have 10, not nine. If you really do have 9, then someone else will have to answer because all I know is that the AD 3600's and 3800's are *supposed* to have HO52 and HO72 axles (10-bolts). Have you read our
axle 3rd member swap/upgrade tech tip? It should answer most questions.... unless you have a swapped in axle in your 3800 and if that's the case, the gurus will have to walk you through identifying it. If you really do have an HO72 in your truck, that donor truck may not have the 3rd member you are looking for as our research indicates that the 4.10 gearing that we're looking for is in the '68 - '72 trucks. But to be sure, follow the steps in the tech tip for removing the rear cover to check the ratio stamped on the ring gear (Step 3 in the tech tip). One never knows, does one?
Thanks,
John
