This is the link - very good interview ( info on tubes at p.47):

http://johnmayer.yuku.com/topic/6379/t/Guitarist-Magazine-UK-cover-feature-scans.html#.UrQPxnRFDIU

It is an interview of a while ago, so maybe he now uses different tubes - but his 'old' 'Continuum/Where the light is' tone is what I am after anyway. I cannot find the interview where he speaks about the power tubes 6L6GC/JJ-TESLA, but he said he was using those back then. In that interview he also said that he really liked 5751 Jan/PHILIPS as they give more headroom to his two-rock amp.

I have installed those tubes (both pre-amp and power) in my TR SP35, and have to say the amp now sounds even closer to JM tone IMO.

Hope this helps.

A.