i had a 94 and had the same problems. i also had to replace both fuel tanks due to the leaks they get around the bands. the light switches would go bad about every 15k the syncro's went bad in my zf5 speed. always kept a position sensor in the glove box. went through 2 turbos. and could never keep up with a slightly modded cummins of any kind. you best bet is to put a cummins in that truck. you can find a decent used p pumped 12valve for 15-2500 grind your own fuel plate (free) marine injectors if you like them some people dont, (200 used) you can get everything you need from cumminsford.com depending on your tranny for around 1000-1400 and never have to wory about the elec. bs that happens with a psd. i am working on putin a cummins in my 78 4wd f350 am looking for about 600 hp with an auto for a daily driver. its a lot of money at first but you will be happy with the outcome of it. they arent very common and if done right and have a few cosmetics done to the truck your son will turn heads everywhere by looks, sound and performance. the ford guys will be wondering why they are getting passed so easily!!!
98 stretched 3500 12 valve, sun roof,#100 plate, nv4500, Valair 475, 16.5* tim, he351 coming soon, , cab stretched 10", afc gutted, mack rack plug and 4gsk waiting, 60 lb springs