[time-nuts] Thunderbolt hardware revisions

[David Garnier]

Hi,

I'm brand new to the time-nut odessy thing so please bear with me. ;-)

I'm in the market to buy a used Thunderbolt, I have found a vendor that's
selling used Thunderbolt receivers and states one can have the choice of 
PCB
revisions A, B or E. 

Does anyone have any specific info or determined the product history of 
these guys?
Any information would be greatly appreciated.

Thanks,

Dave Garnier - wb9own