Ammeter to voltmeter conversion

A good ammeter-to-voltmeter conversion can be done very cleanly without looking hacked. I strongly UNrecommend the hack-job "fix" proposed by the clowns at MAD Electrical; you can do much better. How much it costs depends on whether you do the work yourself or have it done for you. Redline Gauge Works or Williamsons can both do a stealth conversion of stock ammeter to voltmeter for "it must've come that way from the factory!" appearance as seen in the '62 Plymouth here (look closely at the instrument panel; the Alternator gauge now has a scale from 8 to 18 volts rather than the original D at the left and C at the right—and the oil pressure gauge is another never-offered-by-Chrysler item done by one of the gauge specialty houses).

For less money (but more work) you can just buy a Sunpro voltmeter, tear it apart, and mount the old ammeter face over it with excellent, clean results as shown here and here.