99 2500

That is the typical symptom of a failed pressure regulator, pull the vacuum hose at the regulator and you will see gas if it failed

Check rockauto , lots of choices there.

Heck, I usually go 120 miles before my gauge starts moving from full and this is in my 1999 4x4 6.0 gas but it has the 34 gallon tank : )

I had all my gauges and odometer go out once and it was a ground wire that broke of behind the passenger side of engine on top. It is one wire that comes out of wire harness for coils and injectors put on a new eyelet connection and good to go.

Yes can be done in vehicle pretty easy especially if 2wd, have done about 4 different gm vehicles.

That's your oil pump, pressure relief valve is stuck open

If it's a 2 wheel drive it's pretty easy to do, 4 wheel drive is way more difficult

More than likely it is the o-ring where the pickup tube goes into the pump. At this mileage I would just put a new oil pump and o-ring an it will probably be good as new.

That is incorrect, I still have my 1999 NBS 2500 and it says 8600gvw.

Autoanything.com has a good selection

Check your driver door sticker, should say 8600 gvw which was considered HD in 2000 since that was the highest for a 2500 in the 2000 model year .

Looks to have oversize tires on it, maybe 285/75r16. The big tires are sometimes hard to balance, I would take it to a tire shop to check wheel balance .

I fixed mine by removing rivets and turning it around and refastened with stainless bolts.

Maybe this TCI flexplate would fix your problem? http://www.summitracing.com/int/parts/tci-399754/overview/

Check out pickuptrucks.com, they recently did a HD comparison between the GM, Ford and Ram and also compared the gas engines to the diesels in various test empty driving mileage and loaded. Surprisingly the gas engines are almost getting the same mileage. The 2015 6.0L should feel the same or even better than the 454 because of the 6 speed low first gear.