1967-8 RS Gas Cap GM or not?

[Hot Rod Todd]

Hi all, I bought this RS gas cap and it came in a GM box with correct part number 3910189. I bought it on the premise that is was GM NOS but I did not pay ebay price for it. I notice that one just like mine sold for over $180 recently. I also notice that some have screws on the back and some have rivets. Please tell me if mine is an original. I do not see a part number on it anywhere.

[Hot Rod Todd]

One of the front

[Hot Rod Todd]

One of the box with part number.

[Hot Rod Todd]

Here is the ebay auction with the same cap.

http://cgi.ebay.com/ebaymotors/1967-1968-Camaro-ralley-sport-gas-cap-N-O-S-RS-Z-28_W0QQcmdZViewItemQQ_trkparmsZ66Q3a2Q7c65Q3a3Q7c39Q3a1Q7c240Q3a1318QQ_trksidZp3286Q2ec0Q2em14QQhashZitem290295152292QQitemZ290295152292QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

[Tinkerr]

the ones with the rivets are the more desirable ones. i believe they were early over the counter units. the laters units used screws and i don't believe them to be looked upon favorably when the car is being judged.

[1968RSZ28]

Todd -

I just checked the original one on my 02C '68 RS Z/28 and it looks the same as the one in your photos.  There's no part number on my either, only a stamped SM (I believe this stands for Stant Manufacturing) inside a double circle.  I checked the part number and it is correct (it only cost $4.35 in 2-69!).     

Paul 

[Hot Rod Todd]

Thanks Paul, I am glad to know it is a GM. They are paying some premiums for this NOS stuff so anytime I can get a break, I will take it.