I have a 1999 GMC Savana 2500 with 8 lug wheels. It has over 330K miles and I need to replace the rear end. I need to do new brake rotors on the front as well.

So I thot maybe I should swap the rear over to a 6 lug while Im at it and do the rotors to 6 lug in the front as well. Im thinking of this for 2 reasons. 6 lug wheels are way more plentiful and a much greater variety is available than the 8 lug. Also I have a 3:73 rear now but would prefer more of a highway gear. Seems it would be easier to find a different gear ratio with a 6 lug rear.

Would I have to change spindles to go to a 6 lug front brake rotor? If so, would the 1500 6 lug spindles be the same for my ball joints and tie rod ends, etc? Different calipers also I assume?

Here's a dropped spindle question - will dropped spindles from a pickup truck for the same year work on a van? Ive read that they will but cant confirm it for sure.

Thanks for any help!

 

What a whole lot of work and expense for nothing. How often do you change your wheels that this is an issue?

If you do in fact need a rear end, then just do that. Get an axle shop to rebuild it for you. New rotors are easy too, but since they are one with the hub, you may as well do the front bearings too. While the rear brakes are off, do the wheel cylinders and machine the drums.
I had a 95 with a 3.42 rear end, and a 350, and now have an 02 withe the 3.73 and a 350 and the mileage is almost the same.
Believe me when I say.....its a waste of time and money chasing ideas to improve fuel economy on these vans. Whatever you get will never pay off the investment.

 

I think you have over stated the "expense" for nothing. Ive gotta due front rotors, so Im spending the money anyway. Ive gotta due something with my rear, so money is being spent anyway. If I were to do a change, now would be the time to do it. Im thinking about it and weighing options.

So I have to do the rear and I can stay with the 8 lug, or go down to 6 lug. The benefit would be more cost effective options if I want to put some aftermarket wheels on it. The savings in wheels using 6 lug instead of 8 lug puts money in my pocket. Also, the selection is far more with the 6 lug. So not a lot of expense for nothing IMO.

The only real "expense" I would encounter would be changing spindles and calipers on the front. Then, if balljoints and tie rod ends are different it would be more trouble than its worth most likely. But, since I would like to due drop spindles on the front if its possible thats money I would already be spending once again, so its not an added expense.

Thanks for your input. I was curious about the change in gear ratio and your info was valuable. I have a friend that took out 3:42's in an 89 Suburban and put 3:73's in. MPG for him went from 15 down to 11 with the change.

 

If you are looking at going that way, then you might try an auto salvage yard for a whole axle from a lighter gvw van. The 2500 has 2 gvw ratings, the lighter having the 6 lug.
If you rebuild your axle you will need new axle shafts, and what if they don't fit the boss in the differential? I might be too pricey to convert. Try for a swap. While you are pricing used parts, get a set of spindles off that same doner van. Then you have most of what you need.
If you do get an axle and it has a different ratio, then you will have to check with a gm dealership about whether the computer needs flashing to deal with the new ratio, or the speedo and odo will be off, as will the gear shift points.

I am not sure if the emergency brake cable is in any way different, nor am I sure about the diameter of the front hub/rotor. Check a parts store to see if they show a different part number for the 6 lug and 8 lug 2500 on those to confirm.
If you are lucky you will find a 1996-2002 6 lug 2500 express in a junkyard that you can rape for parts.
Have fun.

 

Yea, the junkyard is the way to go on that.

Do the 2003 and up year vans have a different rear than the 1996-2002?

 

Different front and rear brakes and likely the hubs and backing plates too. You need 96 -02 for the same axle with drums.....and same ratio too.