Thank you for the correction.. re : 1967,
I will search what I have and post. whatever I can find re the 67 for you.. most of my material re body type applies only to the 64-65 Skylark..
This anecdotal, per memory.. I was an avid Buick car guy as a teen the 67, 68, during which I scoured a dozen auto grave yards on a regular basis as a hobby, up north near a major N.E. city between 1967 to 73.. dur h.s. and college.. I recall finding Skylarks, typically with the chrome script, but with no Gran Sport emblem that I always looked for and no ( GS till about 1970 -73).. Those Skylarks re 67 - 69 were of the lengthened wheelbase used after the (4300 model/body used only for 64-65). The only hint of any large cu in under the hood re the 67 - 69 was that cryptic white "350" or "400" imprint found on the illuminated side marker lights (yellow forward and red aft) in the rear quarter panels.
I always found that very odd, that Buick was virtue signalling in this case discretely "cu in signaling" !!! to the youth market using those little illuminated side marker lamps after they actually went to the special effort re the 65 Skylark, to create a small rectangular "red background enamaled" badge "Gran Sport"..for only that one model year..... almost three years eariler.. This while they were having their lunch eaten by Malibu, GTO, GTX, Charger, Shelby Cobra crowd. I was always looking for that in your face response by Buick showing they had a credible performance product and while at the salvage yards looking under the hood for performance items. During those years there was very little aftermarket interest in appealing to Buick enthusiast.
A while back I found this ancient 1965 ad per the overt but IMO almost non extant ad campaign for the 65 Skylark, re a 400 cu in, bucket seats, floor shift syncro 3 speed, heavy duty suspension, 7.75 X 14s, perf differential ratios.
Ad is attached..