In his first full season in big leagues, Alex Rodriguez wore this Tacoma Rainers PCL throwback jersey for the Seattle Mariners during their July 31, 1996, game against the Milwaukee Brewers. 20-year-old A-Rod slugged two home runs in the game, a 2-run dinger in the 7th inning and a solo shot in the 9th. They were numbers 23 and 24 on the season, and numbers 28 and 29 for his young career. The uber-talented shortstop had a breakout campaign in '96, winning the AL batting title at a .358 clip, blasting 36 home runs with 123 RBI, and leading the league in doubles (54) and runs scored (141). He made his first of 14 career All-Star games and finished second in AL MVP voting.

The throwback jersey worn only for that single game has “RAINIERS” across the chest in red and navy tackle twill with red and navy piping around the collar and down the front. A Cooperstown Collection tag is found in the lower left front beside a white strip tag with "T.B.C. 7-31-96.” A-Rod has signed the front with “7/31/96 2 HR” inscribed in blue marker. The back has his number “3” in red and navy tackle twill and has been signed a second time with “7/31/96 2 HR” inscribed again in blue marker. The jersey displays solid evidence of game use, with visible turf stains and loose threads throughout. The Tacoma Rainers have been the Marners' Triple-A affiliate in the Pacific Coast League since 1995. They started in the PCL back in 1960 as an affiliate of the S.F. Giants.

There are few images of this 7/31/96 game online, but this site shows both team's throwback jerseys with a glimpse of A-Rod wearing his.

http://www.borchertfield.com/2013/04/turning-back-clock-to-1946.html

Includes a MEARS A10 letter and a Mill Creek LOA (date meant to say 8/26/96) signed by A-Rod. Autographs certified by PSA/DNA.