DeCaff2007
I'm Awesome
Engine knock
Description: Engine knock at startup on 4.3-, 5.7-, or 7.4-liter engines is usually eliminated by using an oil filter with a check valve. If this does not fix it, GM has revised PROMs for the computers and will even replace the main bearings if all else fails. (1990-95)
Yeah, I HIGHLY doubt that GM is going to replace the main bearings on a 30 year old truck, especially on their own dime.