I have 146K miles on mine and it is currently up on jack stands while I replace all the brake lines and fuel lines. The price I am paying for all those years of camping on the beach by the ocean...*sigh*. Doubt you will have those issues with an AZ truck. I figure once I'm done with new stainless brake and fuel lines I'll be good for another 12 years!
Now for some facts: The 8.1L ran from 01-07 in the pickups, but only 01-06 in the burbs. The 01-02 models got the 4L80E trans, 03-06 got the 4L85E. The 85 isn't any "beefier", just some minor upgrades. The Allison was not available in the burbs, it wouldn't fit under the floorpan.
My 4L80E has been bulletproof with regular fluid/filter changes. Both are the electronic version with OD of the old GM TH400, a bulletproof transmission that GM ran for years. Do a Google search, the 4L80E is the preferred trans in many hot rod applications, and they can be built to hold 1000 HP.
The 03 model year did get some upgrades like steering wheel audio controls, digital OnStar, etc. If you are an OnStar fan, be aware that the 01-02 OnStar modules are analog, and do not function since the FCC gave the cell companies the ability to kill analog service. There is NO upgrade, they will never work. 03-04 had dual band sets and can be upgraded to work, 04+ was digital and no worries.
Rear axle on the big block is the GM 14-bolt corporate unit with 10.5" ring gear, another bulletproof component that GM has used for years. Tow rating on the 4.10 gears is 12,000 lbs (GCWR 19,000), 10,500 (17,000) for the 3.73 gears.
GVWR on the truck is 8600, empty with driver and full tank of gas the LT model scales at 6700.
Plan on replacing the factory hitch receiver if you tow heavy, they are junk. new one runs about $150.
Be aware that big block burbs came with a "mandatory" option of AutoRide. This is different on the 2500 than the 1500, in that it is not an air system with auto-leveling. The AutoRide system on the 2500's uses shocks with magnetic fluid, and the Ride Control Computer uses a ride sensor at each corner to vary the viscosity of the fluid at some ridiculous fast rate. Ride is outstanding, you would never think you were in a 3/4 ton truck.
Now for the bad news....the design life on the shocks is around 125,000 miles and they are $250 EACH to replace. I am in the process on installing eBay resistor kits to fool the RCC into thinking shocks are there, and I am installing KYB Monomax's. I hated like heck to lose AutoRide but I just couldn't bring myself to spend $1000 on shocks. Be aware, there is NO SUCH THING as a big block 8.1 Suburban without AutoRide. The 6.0 may or may not have it as it was an option, but it came as a package with the 8.1. Will let you know how it rides with the KYB's when it's all back together.
Overall, great truck with a solid drivetrain. Any other questions I can answer please feel free to PM.
Forgot to mention I have the Helm factory repair manuals if you need any info.
