While looking for a tach transmitter battery solution, I found the following site (click on link below), which has a great deal of information... This gives me what I need to know to hook the items up.
One item I found really interesting... It also states the transmitter can indicate certain ignition system troubles by erratic or unstable operation. The cause of this condition is usually poor distributor point condition or improper dwell adjustment. So, I take that as a built in ignition gauge.
http://www.jalopyjournal.com/forum/t...ctions.467635/
In case something happens to the site link above, I uploaded a .pdf copy for our site copy (assuming I did it correct).
Speaking of transmitter battery, I called nearly a dozen different battery and electronic stores in hopes to find a recent solution. Of course, I struck out; however, several stores recommended using rechargable NiCAD batteries, as these are typically 1.2 - 1.5V, unlike alkaline batteries are typically 1.5 - 1.6V. The original MALLORY and SUN batteries were 1.35V.
I haven't given up on the camera battery holder yet. So far, I've been getting mixed feedback. I like the lithium suggestion, as I would think the voltage would be more stable, but none of the stores could match anything up that is comparible to the size of a AA and voltage both.
Since you guys informed me the tach transmitters are located in several different locations, I've decided to mount it on the inner fender on the driver's side (opposite to the battery regulator on the passenger side inner fender). That way it will be symnetrical and will be easier to access to change out the transmitter battery. It will also be close to all the existing wire harnesses above the steering column/linkage through the fire wall, so I can sneak my new wires along the same routes.