[YoungPup1977]

so I guess you didnt check the front pinion bearing and race when you pulled the pinion seal out....with noises (whine) when letting off the gas vs noise (whine) getting on the gas mean different bearings could be defective......either pinion or carrier bearings, so once you have taken the carrier and pinion out of the housing, you can take them to a machine shop to have the bearings pressed off....again its easy for me to spend other peoples money but I would replace all the bearings meaning I would spend your money and buy the bearing kit to replace all bearings in this differential....GOOD LUCK !!!!!!

oh yea, I almost forgot the other reason for replacing the gears for a higher gear ratio to save on gas....I think you just fix the noise and forget about spending the money on getting different gears...454 CID, no matter what gears you use will only yield 12 miles to the gallon if you are lucky, if you use this truck as a daily maybe a honda is in your future....keep the truck for weekend activities....just an opinion, just like what we all sit on, everyone has one...