youngest players to hit a grand slam in postseason

Ronald Acuña Jr. is the youngest with more than 0 grand slams in a postseason game. He was 20 years and 293 days old in Game 3 of the 2018 NLDS against the Dodgers.

Interpreted as:

youngest players to hit a grand slam in a game in postseason

	NAME	AGE	GRANDSLAM	DATE	TM		OPP	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP
1	Ronald Acuña Jr. R. Acuña Jr.	20-293	1	10/7/2018	ATL	vs	LAD	3	1	1	0	0	1	4	1	0	2	0	0	4	4	1	0	0	0	0
2	Mickey Mantle M. Mantle	21-349	1	10/4/1953	NYY	@	BKN	5	1	1	0	0	1	4	0	0	1	0	0	5	4	1	0		0	0
3	Addison Russell A. Russell	22-283	1	11/1/2016	CHC	@	CLE	5	1	2	1	0	1	6	0	0	1	0	0	5	6	2	0	0	0	0
4	Gil McDougald G. McDougald	23-143	1	10/9/1951	NYY	@	NYG	5	1	1	0	0	1	4	0	0	0	0	0	5	4	1	0		0	0
5	Anthony Volpe A. Volpe	23-184	1	10/29/2024	NYY	vs	LAD	3	3	2	1	0	1	4	1	0	0	2	0	4	6	2	0	0	0	0
6	Francisco Lindor F. Lindor	23-326	1	10/6/2017	CLE	vs	NYY	5	2	1	0	0	1	4	1	0	1	0	0	6	4	1	0	0	1	0
7	Joe Pepitone J. Pepitone	24-005	1	10/14/1964	NYY	@	STL	4	1	1	0	0	1	4	0	0	1	0	0	4	4	1	0	0	0	0
8	Paul Goldschmidt P. Goldschmidt	24-024	1	10/4/2011	ARI	vs	MIL	4	1	2	0	0	1	5	0	0	1	0	0	4	5	1	0	0	0	0
9	Jose Canseco J. Canseco	24-105	1	10/15/1988	OAK	@	LAD	4	1	1	0	0	1	4	0	1	1	1	0	5	4	1	0	0	0	0
10	James Loney J. Loney	24-147	1	10/1/2008	LAD	@	CHC	5	1	1	0	0	1	4	0	0	1	0	0	5	4	1	0	0	0	0
11	Mark Vientos M. Vientos	24-308	1	10/14/2024	NYM	@	LAD	5	1	2	0	0	1	4	0	0	0	0	0	5	5	1	0	0	0	1
12	Rafael Devers R. Devers	24-357	1	10/16/2021	BOS	@	HOU	4	2	1	0	0	1	4	1	0	1	0	0	5	4	1	0	0	0	0
13	Bobby Richardson B. Richardson	25-050	1	10/8/1960	NYY	vs	PIT	5	1	2	0	0	1	6	0	0	1	0	0	5	5	1	0	0	0	0
14	Aramis Ramirez A. Ramirez	25-108	1	10/11/2003	CHC	@	FLA	4	2	3	0	0	2	6	1	0	1	0	0	5	9	2	0	0	0	0
15	Buster Posey B. Posey	25-198	1	10/11/2012	SFG	@	CIN	4	1	1	0	0	1	4	0	0	0	0	0	4	4	1	0	0	0	0
16	Will Clark W. Clark	25-205	1	10/4/1989	SFG	@	CHC	4	4	4	1	0	2	6	1	0	0	0	0	5	11	3	0	0	0	0
17	Alex Bregman A. Bregman	25-210	1	10/26/2019	HOU	@	WSH	5	1	3	0	0	1	5	0	0	0	0	0	5	6	1	0	0	0	0
18	Bill Skowron B. Skowron	25-297	1	10/10/1956	NYY	@	BKN	5	1	1	0	0	1	4	0	0	1	0	0	5	4	1	0	0	0	0
19	Mark Lewis M. Lewis	25-310	1	10/6/1995	CIN	vs	LAD	1	2	1	0	0	1	4	1	0	0	0	0	2	4	1	0	0	1	0
20	Ricky Ledee R. Ledee	25-329	1	10/17/1999	NYY	@	BOS	1	1	1	0	0	1	4	0	0	0	0	0	1	4	1	0	0	0	0
21	Edgardo Alfonzo E. Alfonzo	25-331	1	10/5/1999	NYM	@	ARI	5	2	2	0	0	2	5	0	0	1	0	0	5	8	2	0	0	0	0
22	Adam LaRoche A. LaRoche	25-337	1	10/9/2005	ATL	@	HOU	4	1	2	0	0	1	4	0	0	1	0	0	4	5	1	0	0	0	0
23	Bryson Stott B. Stott	25-363	1	10/4/2023	PHI	vs	MIA	4	1	1	0	0	1	4	0	0	3	0	0	4	4	1	0	0	0	0
24	Enrique Hernández E. Hernández	26-056	1	10/19/2017	LAD	@	CHC	4	3	3	0	0	3	7	1	0	0	0	0	5	12	3	0	0	0	0
25	Michael A. Taylor M. A. Taylor	26-199	1	10/11/2017	WSH	@	CHC	3	1	1	0	0	1	4	1	0	2	0	0	4	4	1	0	0	0	0