Vietnam War veteran Don Clark of Costa Mesa was one of three army soldiers who rode in a gunner truck named Steppenwolf. On Sunday, Clark plans to see the band Steppenwolf for the first time at the OC Fair. (KEVIN CHANG, Daily Pilot / July 21, 2014)

Now, with his appearances at veterans' parades garnering applause rather than spit, Clark speaks of his Vietnam days in fond terms — often, at least. More than once, he refers to his year in combat as a good time, his friends as a good team. And he proudly outlines their creed: namely, that if one member of the company went down, the others would go back to save him.

Whether he'll get to meet his truck's namesake up close, Clark doesn't much care. He just looks forward to an entertaining show, a night out with friends. As to what he would tell Kay if he encountered him, Clark can't think of much beyond thanking him for the music.

Still, a picture might say it best. When the conversation turns to Steppenwolf's legacy — and the fact that the phrase "heavy metal thunder" in "Born to Be Wild" is sometimes credited with giving a musical genre its name — Clark grins, remembering the song's original effect.

"It was something we liked," he says. "And heavy metal — well, we're heavy metal." He gestures to the photos of the old armored truck. "This is heavy metal."

If You Go

Who: John Kay & Steppenwolf, the Grass Roots

Where: Pacific Amphitheatre, OC Fair & Event Center, 88 Fair Drive, Costa Mesa

When: 7:45 p.m. Sunday

Cost: $19.50 to $39.50

Information: (714) 708-1500 or pacamp.com/pa