I agree with Paul. I had a 66 C-20 that had a moderate amount of rear end noise with regular driving. It was however much louder with a camper and crawl through boot installed. I thought mine was loud until I drove one owned by my father in law. He had it "fixed" but It still sounded like a fire truck was following it. He put about 250K miles on it and it still worked when he sold it.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine