Who's is the guitarist?

[Hardbopjazz]

Bags on vibes and Ray Brown on bass, but who is the guitarist? 

[Dmitry]

Martin Mull?

[mikeweil]

A very young Ulf Wakenius?

[Hardbopjazz]

I don't know. I was hoping someone would have the answer.

[sgcim]

Yeah, that's gotta be Ulf. OP probably hooked him up with Bags and Ray.

[JSngry]

A little digging into the image seems to indicate that it was taken at Parnell's, a Seattle club, ca. 1980.

https://en.wikipedia.org/wiki/File:Milt_Jackson_07.jpg

And this article suggests that Parnell's often hired name attractions with local rhythm sections.

http://community.seattletimes.nwsource.com/archive/?date=20060223&slug=parnellobit23m

The original photographer is still(?) reachable: http://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=727988

[sgcim]

I'm taking this to the highest authorities, sir, and we'll have an answer for you very soon.

[sgcim]

I am back with a definitive answer from a jazz guitar website. Within half an hour the guys unanimously agreed that it was.................RON ESCHETE!!!!!