First of all
I don't know much about the suspension stuff but as for the power mods...
As stated above get a turbo back exhaust system or do it cheap with a high flow muffler and stock exhaust. Not sure what the part number is but I know there is a Walker muffler that works out good. Just replace the original muffler and gut the cat and you're good to go.
Get a air intake of some sort on it. If you want to spend some money on it the AFE stage 2 kit looks great. You can make up a cheap TYMAR intake by going to NAPA (or where ever you buy parts) and buy a few clamps and a big paper element filter and you will have basically the same performance as the AFE with filtration equal to the stock filter. Click here
for some part numbers. The instructions are for the 94 - 97's but it basically the same with the SD trucks. I think you can get the stock rubber boot to slip over the filter and not use the exhaust tubing in between on the Superduty's but it may sit in a little better with the tubing.
After that I would get some gauges. Personally I think the intake and exhaust can do no more harm to your engine than the stock intake and exhaust, so why would gauges be absolutely necessary?
Next would be a chip. You will definitly need gauges before adding a chip. There are endless choices for chips. I have one from Tony Wildman and am very happy with it. A lot of people like the chips from DP Tuner
Gears - I would change to whatever it takes to get your rpm back to stock with 3.73 gears and stock tires. Probably 4.30 or 4.56
My truck has 4.10 gears with stock size tires. It probably sacrafices a little fuel economy empty but it is PERFECT for towing. I wouldn't be supprized if it gets better economy towing (6000 lbs or more) with the 4.10's.
Have fun with your truck and hold on to your wallet
96 F-350 CC Dually My TDG Gallery
B codes, head studs, Comp 910 valve springs, stock turbo w/ 1.00 turbine housing
6.0 IC, NAPA 6637 air filter, AeroTurbine 4040XL, ITP Overboost Annihilator,
Quadzilla Commander, electric fuel system w/ regulated return
coolant filter, 203* thermostat
Dually Club Member #53
12/15/07 Greeley, CO w/ stage 1 injectors and Wildman tunes