I got a gauge set to install.The voltmeter instructions say to hook in where the feedwire goes into the fusebox.As we know 56 does not have one.Do I hook it to the accessory terminal on ignition switch or is there somewhere else better?

  

Just hook it to a switched terminal on the ignition switch.  That way it doesn't constantly draw current from the battery when the engine is off.  Also, having it at the ignition switch is a truer measure of available voltage to your entire electrical system as it takes into account any voltage drop caused by the natural resistance of the wiring itself.  With the engine running, if all's well you should see about 14 volts.

Best,

AJ 

A.J.

South Jersey

SMSgt USAF Retired 
1955 Ford Ranch Wagon & a couple of old guitars...Life's Good!