my 04 5.3 (327?) silverado does that shift thing too. there is a switch on the shift lever for racing (has a picture of a trailer going up hill !!?) flick that on and get another 600 rpm's before the bang and chirp. hey, it's waranteed might as well stand on it !!
Chris
p.s. pass that tube of elbow grease and the light bulb repair kit.