OK, here's the deal. I just sold my 2006 2500HD Silverado and Bought a 2008 GMC Sierra 2500HD Z71 duramax diesel. I loaded the bed with 500 pounds of weight plus 100 pounds of tongue weight and the nose was 2.5 inches higher than the rear.

First, I don't think there are any difference anymore between the GMC Sierra and Silverado but could be wrong?

The next question is what makes a 2500HD, a 2500HD and a Z71, a Z71? As stated above, my truck is a 2500HD Z71. I am trying to figure out exactly what I have with this truck.

I do think someone messed with the front torsion bar a little but is that enough to sag the rear? I guess I need to know what the difference is with a 2500HD and a Z71. Then I need to now what you get when the truck is both.

Thanks

 

2500hd- a heavy duty truck, heavy duty shocks, leaf springs, torsion bars, bigger motor and a bigger axle with lower gears (4:10s and not 3:73s)

z71- was most common on older model trucks but now is on the nnbs. just upgraded offside shocks, skid plates, better leaf springs then a regular 1500, towing package, 4x4(usually), lower gears than a regular 1500 (3:73s and not 3:42s)

both- well basically the best of everything. bigger motor, lower gears, HD trailering package, HD leaf springs, HD torsion bars, skid plates and 4x4(on some of the nnbs they have a z71 but it's 2wd drive. still has the benefits of 4x4 but without being 4 wheel drive)

 

so i have a 97 K1500 Z71. 5.7 L
you think i have the 3/42s instead of 3/73s ?

 

That is kind of what I was quessing. I do know I have the 3:73 gears. So basically the 2500HD Duramax Z71 is just a 2500HD with skid plates and a decal.

 

Chevrolet and GMC pick-ups have a factory "rake" to their stance. When they have a load in the bed, or on the tongue they "level out" so to speak. That being said, I know several people who have installed leveling kits on their trucks. This raises the front end to remove that "rake", but causes the frontend to be higher when the truck is carrying a loaded bed or trailer.

 

I looked at the torque adjustment and it can not be adjusted to lower the nose so I guess that confirms someone installed a different torque tube key to lift it. Since I use my truck as a truck the rake does not bother me in the least so I guess I'll purchase OEM keys and get it back to stock.

 

I would look at the keys first before buyin OEM ones. OEM keys can level a truck out, reason for purchasin aftermarkets is that the OEM ones won't lift it high enough or don't achieve the desired stance. Look at your keys and see if they're tightened at all, if they are, then jack it up and lower the keys until you get it back to where you want it

 

You probably have the 3.73
Click the link in my sig line to find out

 

All Duramax's have 3.73 gears no matter what. The Z71 package on 2500HD's have better off road shocks, skidplates, and the G80 locking rear. When you loaded the weight, it wasnt so much sagging as it was just settling onto the last helper spring. The reason it looked so is probably because someone either turned up the stock keys or replaced them with leveling keys.