I believe no documentation as to being an X and it was a small block car or at least frame. The firewall does not look right either, maybe replaced or repaired????
Question .... and first, let me say that this is a nice looking car. That said, I know that the '70 X's came with the up-level 'Custom' trimmed interior and had much of the 'Custom' level exterior brightwork minus the chrome base of hood molding and the rear body chrome moldings (above the rear bumper) ... and this included the wheel well moldings. So, as I have seen in several '71 - '72 X's, the GSX package is present on base-level interiors as well as 'Custom' trim interiors. So, were there '71 or '72 X's produced without wheel well moldings?
It looks like all the dimples are gone so it was either smoothed out or was possibly a factory A/C car that was converted to a non-air car.
I believe this car has been discussed several times. The owner is a board member but not very active. It is a real GSX but not believed to be an original 455 car. It's a very nice car that only needs a new owner and enjoyed...
I think this car sold at Central Pa Auto Auction 's classic car auction a few years ago . Could be wrong . The car I saw sold was one of Grant Millers cars , he owns the auction.
Was recently listed in Hemmings for $69,995 obo. https://www.hemmings.com/classifieds/cars-for-sale/buick/gsx/2079499.html#&gid=1&pid=35
Yes stunning car, even if it was a 350 x, looks like it was a good car to start with, someone did a nice job from the pictures.