80's/90's Chassis Dimensions, again

[DonMoose]

I don't want to look dimmer than I actually am, but the threads I read about chassis dimensions left me a bit lost.

The output tube spacing of 2.5" seems clear, but the preamp tube spacing of 1.5" makes me confused. A 12Ax7 in a socket is about 1" in diameter, so that 1.5" can't be center-to-center, can it?

So, if it's 1.5" open space between the 12's it must be 2.5" open space between the outputs ... right?

The next dimension question is the control spacing.
Jacks->Vol
Vol->switch1
switch1->switch2
switch2->switch3
switch3->T
T->M
M->B
B->Lvl
Lvl->Ratio
Ratio->MV
MV->Pres

The overall dimensions I do get.

Thanks, y'all!