Tom,
About 6 years ago, I found a stash of Mavic GP4s GP330s and GP280s at a local shop. I was on a wheel building binge, and to the best of my recollection there were two GP 4 rims, the older style with a smaller rim side wall height (lighter) and a GP4 rim with a "taller" sidewall height (stronger). I purchased two pair of the smaller height (lighter)GP4s in both gold label and newer elongated label/descriptor yellow and purple form. The wider sidewall GP4 had the newer, larger, purple and yellow label. So to answer your question, there is no answer.
Carl Gonzalez Bay Village, OH
Responding to:
> Everytime I think I know a bit, along comes another item to confound me.
>First question. There appears to be two Mavic GP 4 rims out there. An
earlier lighter version (around 400 grams) and a later version
(the one I am familiar with), designed to be super strong and weigh the same
as a middling clincher rim at 480 grams. Is there a way from the labels to
detect which is which? Of course if you have a bare rim, you can weigh it,
but the ones I have are in built wheels.