Here is the hyper-linked interactive version of my screen grab.
http://paintref.com/cgi-bin/colorcod...nuf=GM&rows=50
Now if your guy's supplier can't get a good match to one of these numbers find a different supplier or more capable help at his current supplier. A phone call to PPG or email should sort this out in any case. They do have pro help lines for these issues.
In answer to your question this shade ran from 67-69 on Chevy/GMC trucks.