Can anyone tell me the difference between the emissions routing decal (found on the radiator support) code YCM and YCW? Neither GM nor any of the after market vendors I have talked to can tell me. In the interest of accuracy I would like to apply a new one to my Elky but don't know which one to buy. Thanks for your help.

They are both for a 5.0L engine. The YCM decal shows a "tank pressure control valve" hooked up to a line from the charcoal canister. The YCW does not.

Thanks Ernie. I'll get back under the hood and confirm what I actually have. Had a feeling you would know. Thanks again.

Back from under the hood. . . I guess now the question is - is the control valve on the line, from the cannister, that terminates at the intake manifold, just behind the upper radiator hose? Or is it somewhere between the cannister and something else? I may not have one. As always I really appreciate the help.

Look at the line on the charcoal canister going to the gas tank. The tank pressure control valve will be in the hose between the charcoal canister and the gas tank. If the hose just goes from the charcoal canister to the hard line on the frame rail then you have YCW. If you find another valve in that line with another hose going to the canister control valve then you have YCM.

Thanks again. It's just like you said. The hose goes to the hard line on the frame rail, back to the fuel tank. How did you get so smart? Thanks again for the advice. Ordered a new decal today.

How did you get so smart?
Well, first I was Young and Stupid...