noise
 

hey guys new here, i have two questions about my truck its a 1998 sierra k1500 extended cab 4wd. the first question is about a gear drive noise, when i am driving down the road at average speed and i go to pass another car i step on the gas and it kicks down into passing gear the rpm's go up over 3000 rpm's and it sounds like i have a gear drive, i have replaced the idler pulley and the tensioner assembly and new belt, it does not do it when the truck is in park and you rev it over 3000 rpm's. 2nd question is about a popping noise in front end of truck when backing out of driveway, new balljoints, tie rods, idler arm and bracket, pitman arm, and stabilizer links and bushings and new shocks. sorry about the long post just looking for info to fix these problems any info would be greatly appreciated. thanks again

RE: noise
 

Im not sure what you mean when you wrote it sounds like a gear drive but as far as the 2nd one sound to me like you need u-joints. One way to check them is to try and turn your drive shafts by hand to see if there is any play.