Harris then used his bat to help Post 158 claim a thrilling 6-4, nine-inning District 14 win over host Cape Girardeau Ford & Sons.
The non-district nightcap of Wednesday's doubleheader at Capaha Field was still underway at press time.
"It was just a great game all around," said Jackson coach Mark Lewis, whose squad improved to 16-5 overall and 2-1 in district play. "Both clubs fought hard. It could have gone either way."
Cape (12-11, 2-1), which claimed a 4-3 district win at Jackson on June 6, rallied from an early 2-0 deficit to forge a 2-2 tie and appeared poised to win in its final regulation at-bat.
Harris went to his knees and came up with the scorched ball to his right. He fired to first base to force extra innings.
"It was good to make the play," Harris said. "I only started playing third base about a week ago. ... I was glad to keep us in the ballgame."
Harris also made a nice play on the previous batter, fielding Alex McRaven's bunt and firing for the second out of the inning.
"Cody had a heck of a game," Jackson's Alex Bolen said. "He saved us at the end."
Harris put Post 158 ahead for good when his bases-loaded, one-out single drove in two. Cody Heisserer added a two-RBI double.
"It's nice to have a game like that," Harris said.
Cape wasn't done, using two hits, two walks and an error to score twice in the bottom of the ninth. But Post 63 stranded the bases loaded.
"One thing about this team, they don't quit," Cape coach Steve Williams said.
Bolen's two-run homer to left field at spacious Capaha gave Jackson a 2-0 lead in the first inning. Post 158 did not score again until the ninth.
Cape scratched out an unearned run in the third inning, Siebert delivering an RBI single, and tied it in the fifth when Andrew Williams tripled and scored on Logan Henson's single.
Both starting pitchers were impressive.
Jackson's Joel Koenig worked 7 2/3 innings, allowing seven hits and two runs, one earned. He struck out two and walked three.
"He kept his pitch count down, which allowed him to go deep in the game," Lewis said.
Cape's Alex Davie went 6 2/3 innings, allowing nine hits and two runs. He struck out seven and walked two.
"Alex pitched well," Williams said.
Caleb Rowald notched the win as he pitched the final 1 1/3 innings. Luke Hinkebein, who worked the last 2 1/3 innings, took the loss.
Jackson had 15 hits, led by Ian Householder with three. Harris, Bolen, Laban Petzoldt and Chase Simmons all added two hits.
Siebert had three of Cape's nine hits. Williams and Trey Gardner added two each.
Both squads stranded 12 runners. Jackson committed all three of the game's errors.
"Both teams had opportunities," Williams said. "We failed to get a couple of bunts down that hurt us."