That Cowboys jersey wasn't a throwback, but Jerry's own alternate "double star" jersey. I don't think they kept it for more than a few years.
I was living in Dallas back then and remember unadulterated hate for this jersey on the part of the media and fans. Not only was it ugly, but the team usually lost the games when they wore them.
I'm pretty sure the 49ers were wearing their throwback uniform in that game. They got hot after their throwback game and kept them all season.