Good to know, I will split the topic first, then respond. Then I think the response will appear in the new posts list.
Here's Manley's tech support info:
Paul Fargo, Technical Support
Manley Labs Service Center
1419 E. Sierra Vista dr. Globe, AZ 85501
TEL: (928) 425-9333 FAX: (928) 425-9787
<http://www.manleylabs.com>
<mailto:service@manleylabs.com>
At RMAF a Manley factory rep (don't remember who) said they are not using GT tubes in the Snapper now, I encouraged them to use them, but whatever reason, blablabla. He was unaware that Mitch Margoles designed the Groove Tubes E34Ls. He seemed relieved that he was "not with the company anymore..." My interpretation, that's all. So I don't know what the deal is with Manley/Groove Tubes nowadays.