Konrad Reuland's heart was always strong.

For 29 years, it kept its rhythm inside his chest throughout Reuland's career at Stanford and in the NFL, until his sudden death in December from a brain aneurysm.

Now, it has a new home inside Rod Carew, keeping the 71-year-old Hall of Famer alive thanks to a transplant four days after Reuland's passing.

"In terms of health, his heart was a Ferrari," Reuland's mother, Mary, told the San Jose Mercury News this week.

Reuland's aneurysm burst on Nov. 30 and required a 17-hour surgery. Just seven months earlier, the young athlete had signed up to be an organ donor. On Dec. 12, he died, but Mary spent those final moments of her son's life with her head on his chest, listening to the sounds it made.

"I memorized it. And I said, 'I hope I get to hear this again one day.'"

Earlier this year, she did. When the Reuland and Carew families met for the first time on March 2, she pressed a stethoscope to Rod's chest and listened. Once again, she heard her son's heart pumping.

It roared just as it did when Konrad was a high school All-American and one of the nation's top 100 recruits as a tight end at Mission Viejo, a football powerhouse. He ended up signing with Notre Dame and transferred to Stanford after the 2007 season to play for second-year coach Jim Harbaugh. Reuland played out his final two seasons and fought to land on an active NFL roster after going undrafted in 2011. In 2012-13, he played in 26 games for the New York Jets, catching 12 passes.

In 2014, he ended up with the Baltimore Ravens, playing two seasons for his college coach's brother, John Harbaugh. He started one game and played in four.

When Reuland suffered his aneurysm, he was on a treadmill, still fighting for his dream, trying to get back on an NFL roster after being released in August.

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Carew suffered a major heart attack on a golf course on Sept. 20, 2015. He flatlined twice, but survived. Doctors spent six hours installing a Left Ventricular Assist Device (LVAD), which served the heart's function but left Carew so weak, he required a seven-week hospital stay in the wake of the surgery. He and his wife, Rhonda, eventually struck up a partnership with the American Heart Association, founding a campaign called "The Heart of 29." It was named after his jersey number with the Twins and Angels and helps encourage early screenings for improved heart health -- it was also, coincidentally, the age Konrad was when he died.

Doctors found a subdural hematoma in Carew's brain last July, which caused hallucinations and kept him from being eligible for a transplant until Nov. 18 of this year. By Dec. 9, he was moved to a higher priority on the list and had Reuland's heart a week later.

Since learning his donor's identity, Carew has made regular visits to Reuland's final resting place.

"I just thank him for saving my life and putting a roaring heart inside my body," Carew said. "We have a long way to go together."

On April 4 -- what would have been Reuland's 30th birthday -- Rod and Rhonda showed up to the grave alongside Reuland's parents. Carew brought a baseball with a message written in pen.

"Happy Birthday, Konrad. I promise to always care for your very priceless gifts. Until we meet again, I remain forever your brother in Christ.

"Signed, Rod Carew."

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The relationship between the Reulands and Carews is a rare one. Organ donations are always kept anonymous for at least a year, allowing families to process their loved one's death and to surpass the period when a recipient's body is at the highest risk to reject the organ.

However, just days after Reuland's death, his family noticed news stories about Carew receiving a heart and kidney and couldn't help but wonder. After all, Reuland had actually met Rod 20 years earlier, when Konrad was 11 years old.

"'You know I met Rod Carew!'" Mary quoted her son as saying when he came home from school that day, relaying the tale to BaltimoreRavens.com about her son's excitement two decades earlier. "That's how it was the whole rest of the day. It was really kind of cute."

Mary looked up details from Carew's operation and discovered the truth. 

"I almost fell over," she said. "I started hearing from so many people, 'Is it Rod Carew?' Then, I couldn't let it go. It was like something that festers. I needed to know."

By January, she placed a call to OneLegacy, the national organ donor network.

"I said, 'Listen, this train has left the station, it's really hard for me, but we need to know, was it Rod Carew who got my son's heart and kidney?'" Mary said. "She was like, 'We've never heard of anyone calling with the name [of a recipient].' She paused for the longest time and said, 'Yes, it is.'"

The American Heart Association set up the first meeting and the two families have gotten together several times since. 

When the Carews first walked up to the Reuland's home on that warm March day in San Juan Capistrano, Mary's first message was simple.

"You're part of our family now," she told the Baltimore Ravens' website.  

"Forever," Carew said. "I will take care of this one because I've been given a second chance, and God knows how I feel and what I'm going to do for him."