MDTahoe, I got the shimms for the crank sensor. For one the sensor on the 2500hd is above the starter at the bellhouseing, so you have to take the starter off which is only 2 bolts and then a 10mm to get the sensor out. Getting the sensor out isn't as easy as you would think if you don't have small hands. I put one shimm on and it made it code earlier than it ever had so I put the second one on and it would hardly stay started so I just went and bought a new sensor for $62 and some change, put that in and haven't had a code since. Thanks for all the advice if I had to do it again I would just go straight for a new sensor, saves a lot of time crawling under the truck and racking your knuckles.

 

They key to the shims was the warping of the plastic timing cover. Since your crank sensor was not in the timing cover that could not have been the problem.

 

I have a 04 silverado2500hd the engine light comes on flashing when reaching speed 65 mpg

 

I have a 2004 Silverado 2500hd with the same problem im droping it off 1-26 Monday, you change the shim yet