Just bought a stock 00' 2500 manual with 147k miles. I'd like to maximize the life of the engine/tranny and fuel mileage but tow boat, trailer, or four wheelers etc. I need suggestions on what to check and/or change as far as the engine/tranny(belts, fluids, injectors, fuel pump, etc.) and aftermarket upgrades for mileage and longevity(programmer, sensors, gauges, etc.) but keep down on the cost or make upgrades in stages but not cause undue stress on the transmission or other areas of the motor with the upgrades. Any help appreciated!!

 

The best advise I can give is to get gauges. Fuel pressure, boost, and EGT's (pyrometer). Since you have a manual you wont need a tranny temp gauge. Those three gauges can tell you just about everything you need to know, at anytime. They're worth their weight in gold since you'll be able to tell if there's a problem and possibly be able to alleviate a potential problem. If you decide to get a fueling box, some have digital monitor displays that are basically an all in one gauge if you dont like the separate gauge look.

 

Gauges and fuel system. Fluid changing for diffs, tc,and trans.

 

Your goals sound a lot like mine. I have been upgrading as things need replacing...
Got an edge juice with attitude (didn't tap the VP wire) for the gauges and found out the fuel pressure was low, so I got a fass.
Exhaust was needed to pass safety, so it was replaced with 4".
It also runs synthetic oil.
I will be upgrading the air filter to an Amsoil 4091 w/outerwear. I also switched the hubs to lockouts (freespin) for mileage, and cheaper/serviceable bearings, and less wear on the shafts and front diff.

The only other mods I may do is the chevy rear brake cylinder, rebuild the tranny with quad 4x4 stuff to eliminate the 5th gear nut issue if/when that happens and 3rd gen wheels.

I couldn't be happier with the mods and truck in general!