you might try contacting camaro central. they used to sell them (pretty pricey) they show a pair of used ones but say they are not available at the time. they are very hard to come by even used. if you find someone who sells them please post as mine are shot and i would like to purchase also.
they go just under the front of your buckets and bolt to the front track bolts. they're basically to cover the tracks for cosmetic looks. also just did google search dadgonebroke and found a new pr. for 139.00 chicago muscle car parts if your interested.
I've ordered from Chicago Muscle Car parts and the two lap vents I got were perfect. Be prepared to wait he does not get in a hurry to ship and their site sometimes says they are not accepting orders at this time. He often has hard to find parts. You might also try Doug at camaropartsworld.com it looks like his site is being revamped but his email and phone number there and he has always delivered quality parts for me. I generally just call or email. Cheers