I've been searching for a while on the correct color code for my bumpers on my H3. Apparently, these paint codes are not included in the build sheets, and do not come up when searching (this according to a dealer owned body shop). They said they just mix to match.
I wasn't exactly happy with that, so I continued my searching, and did finally end up with the correct paint code - at least for mine, which is the darker color. I see two prominent colors when looking at photos of different hummers - a dark color, and a lighter color.

For mine: Dark Smoke Gray / WA501F

I saw reference to another color (on this forum) that was NOT correct for me, so I thought I put this out here in case others need it. I also will include the mix sheet I received from Advanced Auto (who graciously mixed up a text batch to ensure it was correct).

 

Hello brothapig. In your post you referenced a darker color for your H3 bumper and a lighter color. I’ve been looking, but can’t find reference to the lighter color for my 2006 H3 bumper. Can you point me to it? Thank you.

 

Just to post some additional info, this is a PERFECT match to the Silver Front Skid Plate/Bumper on my 2008 Alpha.

 

Bud, as I didn't need the lighter color, I didn't do any further digging. I worked with the gentleman at Advanced Auto to find this color. It was listed as a GM color, but not specifically for the bumper of an H3. Sorry I couldn't help you.