Ah, that's right. I forgot they were NNO. Here's the players I know of in the 1990 set (Steinbach is a new one to me):
Roberto Clemente, Ty Cobb, Tony Gwynn, Barry Larkin, Eric Davis, Andy Van Slyke, Ken Griffey Jr., Bo Jackson, Jose Canseco, Bobby Bonilla, Don Mattingly, Kirby Puckett, Cal Ripken Jr., Nolan Ryan, Bret Saberhagen, Craig Biggio, Chris Sabo, Robin Yount
I'll see what else I can find available on eBay later today. Based on the surrounding years being 62-64 in the set, it looks like we may have a long way to go on figuring this one out.