Gene Simmons, Paul Stanley and Peter Criss Attend Ace Frehley's Funeral

Ace Frehley did the impossible ... bringing his former bandmates back together to celebrate him at a private funeral held earlier this week in the Bronx.

Eddie Trunk -- a well-known radio DJ and close friend of the band for many years -- shared a summary of the intimate affair ... as well as a photo of what looks like Ace's grave marker.

The plaque has Ace's full name written out with the dates of his birth and death sitting above the Bible verse John 14: 1-3, 27 ... which reads, in part, "Let not your heart be troubled, neither let it be afraid" ... so, it sounds like Ace is trying to provide comfort even though he's gone now.

Trunk says it's been an emotional couple of days for everyone ... but adds it was nice to see people in Ace's world he's known for years -- former KISS manager Doc McGhee, actor and stuntman Chuck Zito, and more were reportedly in attendance -- and other friends of Ace he got a chance to meet for the first time.

Eddie says Gene Simmons, Paul Stanley, and Peter Criss all congregated to pay their respects ... though he didn't provide any details about their interactions at the service.

Eddie did allude to a possible public celebration of life in the form of a tribute concert for Ace in the future ... though he isn't rushing to drop specific details for the event yet.

We broke the story ... Ace was hospitalized after falling and hitting his head at the studio last month, causing a brain bleed. His family made the difficult decision to take him off life support about a week ago. Tributes came flooding in for Ace from all over the rock world after his death.

Frehley was 74.