Both of these Hot Wheels ’57 T-Birds are from the first year of its release, 1978. I found the white one on eBay, the yellow one came from The Dealer.
Early versions of this car could be found both with and without the small round porthole window on the side. But after 1982, Hot Wheels settled on the casting without the porthole for its many variations of this long-running model.
Of course, the original Hot Wheels T-Bird is the Classic ’57 from 1969.