Nice, the Tahoe is sort of the little brother of my Yukon, same basic body but mine has the Corvette LS1 Gen III Vortec 5.7l V8 with the 4spd Automatic 4l60E tranny. I modified the original design by changing the rear differential gears and bearings to Yukon gears (the maker not a GMC Yulkon part) as well as changing out the open carrier to a Yukon Limited Slip version as well as replacing the rear shaft halves (both sides) with (you guessed it) Yukon shafts and wheel bearings. I also replaced the battery with two new heavy duty batteries (the Yukon has an extra area just for a second battery built in). Rebuilt the tranny with speed shift kit (new solenoids and valve body) as well as replacing most of the suspension parts with heavy duty versions. The air intake was replaced with a cold air intake (to prevent water from getting into the throttle body, not to do any magical increases in power), and added and redirected the PCV lines to twin oil catch cans, and replaced the valve cover air line that went to the throttle body (and dumped oil directly into it) with a filter and plugged the line to the air intake hood. Finally I removed the OEM throttle body resonator (which was doing little more than heating up the air intake before it hit the throttle body, thus robbing it of power). After that I replaced the OEM distributor with a competition version as well as taking out the OEM CPFI fuel injector with a new Multiport MPFI injector. Replacement of the CPFI with the MPFI ended a LOT of Error codes showing random misfire conditions. I found out that the standard plugs used in this engine will not last more than a few months before misfiring, so I replaced them with Iridium plugs. After doing a full rebuild of the valves (two jammed because of the CPFI failure) the engine runs so smothly that I actually went off one time and left my keys in the ignition with the motor running and got myself locked out because I didn't realize it was running. Finally I replaced the fuel pump and sensor assembly due to a problem the OEM version was having. With the replacement of all the U Joints the mechanical paerts have almost all been replaced or rebuilt now. ( and yes, it cost me a small fortune - over $8000), but I could not have bought a new truck with all the features this one now has for anywhere near the price.
Beyond the mechanical revisions, I swapped the tires and wheels (245x750R15) with 17" wheels and 35x12.5R17 Nitto AT Terra Grappler tires. This caused a problem with the wheel wells scrapping, but rather than put extra tension on the suspension and raising the center of gravity, I opted to have the body modified by cutting out and flaring the fenders to fit over the new tires as well as using wheels with a 6" negative offset. After all that it has been just a matter of modifying the body and interior to add the extra abilities I wanted.
