Tachometer drive gearbox ratio

Hi.
Is the TACHOMETER DRIVE GEARBOX 2:1 or 1:1 ratio?
Is it the same of the early 1968/9 Commando?
BG1508/5 that is 1:1 wiith what tachometer ratio works well?
Thank you.
Piero

Hi Piero,
I believe you already asked this question and Thomas and I both confirmed it was a 1:1 ratio. The early Commando drive is a 2:1 ratio. The P11/Atlas tachometers are 2:1 ratio instruments while the Commando tachometers are 4:1 ratio.

Hi Ron,
thank you so much.
Pieo