In 1972 Chevrolet offered a special promotional package called Highlander that offered option grouping packages at a discount along with a unique interior trim package most notably identified by plaid interior trim inserts. The packages were available in trucks, Suburbans and Blazers. They're usually easily identifiable on the SPID because of the YGX promotion codes. But since SPIDs can be wonky...I saw your tilt and A/C...and then the unlabeled blue 677 at the bottom and thought it might be one of those "hidden" Highlanders. If you've got your original dash pad and it's black...I'm guessing it might be a Highlander. Here's a thread about Blazer Highlanders started by a true expert in the field, SS Tim:
http://67-72chevytrucks.com/vboard/s...d.php?t=635033