Here is a picture from "Some Kind of Monster", a documentary about the making of St. Anger. We see a Peavey 5150 sitting under one of James' Marshalls. It's unclear whether this actually belonged to James.

Eddie Van Halen used the Peavey 5150 120-Watt Head during the recording of the "Balance" album, as evidenced by images found through Google search.

Used on Alice in Chains' self-titled album in 1995.

I also used a Les Paul through a Peavey 5150 amp. Ed [Van Halen] gave me three stacks after we did the tour with him a few years ago. He'd just come out with his new Music Man guitar and the 5150 heads, and I asked him if I could maybe buy one off him. When I came back home after the tour, there were three stacks waiting for me in the fucking garage! [laughs] The guy was totally f-ing cool! Plus, he gave me a couple of his guitars, too.

In this Guitar Player interview, Satriani states that he “ha[s] a few original Peavey 5150s”. The article goes on to share signal chains from Satriani's personal notebook, which reveals that the 5150s were used on "Smooth Soul" and "Forever and Ever".

“Smooth Soul”

Melodies: MCO#1, Peavey 5150 Solo: KSR Orthos Rhythm Guitars: Gibson Custom Shop goldtop, Korg G4 Rotary Speaker, Fender ’59 Tweed Twin, Wells amp into Fender Deluxe

(...) “Forever and Ever”

Intro/Outro Guitar/Rhythm Guitars: JS25ART #47, Mezzabarba M Zero Melody: MCO #1, Peavey 5150 Solo: JS25ART #47, Peavey 5150

Another one of Satriani's Peavey 5150s was sold on Reverb.com via Bananas at Large.

https://www.youtube.com/watch?v=W-CwfTXN4fE

Spotted at 6:02.

Thurston can clearly be seen playing the amp throughout this show.

In a 1990s photo from Photobucket, Buckethead is shown using a Peavey 5150 120-Watt Head amplifier.

In this interview with Guitarworld, Alex talked about his gear on previous albums. He mentions a Peavey 5150 he used on Counterparts.

I used a Peavey 5150 and a 100-watt Marshall JCM800. I had a [Roland] JC-120 as well that I used for some clean things, but primarily everything was done on the Peavey and the Marshall.

in this video of a concert in 1996, you can see pat smear using a peavey 5150 mk1. he used this in the very early days of the band, and possibly could have been used to record there first album. there is a clear shot of it at 4:15.

In this picture taken from one of MCR’s earliest gigs, you can see Ray playing through a Peavey 5150 120w Head.

https://youtu.be/OLFqtktdG1s

A peavey 5150 head can be seen to the left of Lee, whilst recording sempiternal