I can't believe that after all the advice you've been given to get your truck to a driveline shop that knows what it's doing (in two different threads), you're still here struggling and asking the same question.

 

who makes the drop kit, and how much is the drop?

 

I know what your saying, but know one seems to have the answers. Or I get too many mixed responses.
It comes down to this, I lowered the truck, it vibrates, I shimed the axle all different directions and using different shims, that didn't work, so I had the carrier bearing raised, that helped the take off shake, but it still vibrated at other speeds...........
You tell me what I should do next..........I'm all ears!

Jim

 

McGaughy rear drop, adjustable hangers and shackles (I used the 3" drop holes, The lowest hanger hole and the lowest shackle hole).
The front is lowered using Belltech 2" lowering spindles.
The truck still has a slight rake to it. If I use the upper shackle hole, I will gain another 1/2" drop.
McGaughy is no help to my issues. I found that out quick!

Jim

 

PM sent . . 4 wheel drive shop?

 

If it were me (actually it was me, I busted my driveshaft and had to deal with this very issue), I would sit down with the Yellow Pages book or Yahoo Yellow Pages online and start calling driveline shops.

When calling, I would ask them if they are knowledgable in the area of driveline angles. I would ask them if they were experienced in diagnosing and correcting vibrations due to improper driveline angles. I would not use the terms 'pinion angle' or 'transmission output shaft angle' until they themselves used those terms. I would let them ask if I had a 1-piece or a 2-piece driveshaft. In other words, I would let my experience of interacting with them determine if they were in fact competent in this area.

I had to do this exact thing. I spent two days on the phone and online, taking notes, getting a little bit of knowledge here, some there, piecing it all together eventually so I could make a decision as to what to do. I called some places twice, some three times, because some of the knowledge I got from one place helped me understand what another place had told me. It was a tedious process, but eventually I reached a point where I felt like I knew enough to take some action.

In the end, I went to two local places who measured my angles. Both places came up with the exact same measurements (tranny output shaft down 4 degrees, pinion up 7 degrees), both correctly diagnosed the problem and said what needed to happen (pinion needs to come down), but neither had ideas how to correct it.

In the end, on my 3rd call to Hotchkis, we found a solution - we used the lower control arms from their Impala SS axle relocation kit, which have the exact same mounts, diameter, etc. as the Avalanche but were 3/4" longer. This brought down the pinion 4 degrees so my angles were 4/3 instead of 4/7, eliminating the vibration. Actually, it was better than even angles because the added power from the blower would even out the angles under load.

Hope this helps. At the end of the day, you're going to have to figure out what the problem is, but I'm sure there are resources out there local to you that you can use.