Does anyone know if there are different wattages on the little bullet bulbs that go into all the dash warning lights and rocker switches?

I installed a 2" tach in one of the two accessary spots to the right of the instrument cluster and picked dash lite voltage off the little general light above the emergency flashers and all the other rocker switches and the light in the tach is very dim even at full rheostat.

I'm thinking either someone put a lower wattage bullet bulb (they all look the same to me) in the tach or else (much more bizarre) there is a lower voltage supplied to that particular bulb. Or stranger still it's just designed that way(??).

Hey, I'm a mechanical engineer here just feeling my way around this electrical stuff and I admit these are questions I can answer tomorrow by popping off the center console and the tach and applying a multimeter but I thought I'd run by the real experts on the Brichboard first.

Thanks in advance...

Robb