Wow, that is amazingly low mileage, GREAT find.
In response to your first question, GMT 400 describes the generation of Tahoe that we own. GMT 400 Tahoe is first generation (approx. 1995-2000), GMT 800 is second generation (approx 2000-2006), and GMT 900 is third generation (2007-current).
More information regarding GM vehicle platforms here;
GM GMT Platform.
In regards to your second set of questions regarding my vehicle, I had the grille painted but I did not do it myself so I do not know all of the work involved in doing it. I have Stillen fender flares on my vehicle and they are surely the best looking fender flares available for our vehicles, I would recommend them for sure.
Link to the product here;
Stillen Fender Flare Kit
I like the black trim on the vehicle, but a lot of other members have removed it without problems, it is just held in place by a strong adhesive as far as I know, no drilling or holes to worry about at least.
The xenon HID modification is one of my favorites, it looks great as well as greatly increases light output at night. By the book, xenon HID is not supposed to be used in reflector headlamps and there are members who espouse that you need to install projector headlamps in order to correctly perform a xenon HID conversion, but I prefer the appearance of the OEM headlamps, so it is surely not necessary and it still does not blind oncoming traffic as others have tried to espouse.
I replaced my original bumpers with Chevrolet Tahoe Z71 bumpers, both front and rear and then had them painted to match my vehicle. It was difficult to find these bumpers, I had to get the front one shipped from a salvage yard in California.
I found the front bumper by utilizing
Car-Part.com to search a nationwide database of recycled automotive parts. I found the rear bumper by stumbling across one on my local
Craigslist.
And finally, the GMC Yukon Denali console pics can be found on page two of my CarDomain, here is one picture;
Hopefully this helps, if you have any other questions just ask. I have been a proud owner of this vehicle for nearly a decade now, so I have a decent knowledge of these vehicles. Take care, and keep the miles on that jewel low!
