We always just called him “Bundy,” or “Billy Bundy.” It was rarely “Bill,” and certainly never “William.”

The rest of the world now knows him as John Gacy’s 19th victim. But to our group of teenagers, Bundy was so much more.

He was our friend with the quick grin and mischievous twinkle in his eye, who dressed in blue jean overalls and loved a good party.

Bundy was identified last week after 35 long years, thanks to DNA testing. I got the call about it from one of his best friends back then, Richard Dennis.

“I have some grave news,” Richard, also one of my oldest and dearest friends, said to me on the phone last week. I was thinking he was sick or something by the way he said it, but it wasn’t about him at all. Richard called to tell me what we’d assumed for decades: Bundy had been positively identified as a Gacy victim. He was the 19th person to be found in Gacy’s hellhole.

Bundy was part of our close-knit circle of neighborhood friends, who all lived near Irving Park Road and Clarendon Avenue. He had disappeared without a trace in October 1976 after telling his family he was headed to a party. For the longest time we looked for him and expected him to show back up. But he never did.

We speculated what could have happened. He had been flashing around about $800, a lot of cash for any of us as we were not from wealthy families. He had bragged about some construction job on the Northwest Side, but how would he earn that much in such a short time?

When he disappeared, there were two theories. We all wondered, had he stolen that money from someone and they found him and did something to him? Or had he taken off to California or somewhere and would come home when he ran out of money?

Two years later, Gacy was busted. We wondered, but nothing ever came of it. The years went by. We grew up and moved on. We never saw Bundy again. But we never forgot him either.

So when Richard called, the fun memories of being a teen with Bundy came flooding back. My high school graduation party, and hanging out at Addison Rocks, Montrose Harbor, Foster Beach, and around the basketball courts at Disney School, a central location to many of our houses. Drinking Strawberry Boone’s Farm, sneaking into the Aragon for concerts, chilling out at the Rock Garden — now the Peace Garden — at Buena and the lakefront.

Richard remembered how Bundy was an “excellent athlete.” We laughed as he recalled how when they were 12 or 13, they’d play a tag-like game called, “Catch the Weaver.”

“We bobbed and weaved like a boxer,” Richard explained of the game. “We used to say ‘nice weave’ to Bundy, because we tried to catch him, but that dude was way too fast. He had some good moves, man.”

The news about Bundy was heartbreaking, but in its own way, finding out was an unexpected but somewhat welcome Christmas present. At least we now know what happened all those years ago to our good buddy.

So may he rest in peace, finally.

Ho, ho, ho happenings… Grab the kids and head over to Brunch, 644 N. Orleans St., on Dec. 10, because Santa will be there from 7:30 to 11 a.m.!

O’Donovan’s, 2100 W. Irving Park Rd., holds its holiday customer appreciation party 7 to 9 p.m., Dec. 8. A minimum suggested holiday donation of $10 gets you complimentary cocktails, appetizers. Proceeds benefit Christopher House, helping at- risk kids and their families.