I think this string started with gauges for a '64. So, the ammeter I have in front of me is from a 1964 Chrysler and exactly which model is uncertain but probably a New Yorker. The back of this ammeter is actually a solid piece of metal with sturdy stud terminals. The movement is a needle and magnet assembly on a bearing with the magnet over the metal that carries the current. The current and the direction of the current passing through the strip and the magnet determine the direction and magnitude of needle deflection. The needle is centered by the round little magnet centered in two fingures of metal; no spring. Pretty darned simple. A shunt ammeter is different than above and is a millivolt meter measuring voltage across a known resistance, that will generally be very low for auto applications, and the meter can then be calibrated accurately in amperes (although it does not have to be). The '63 dash I have here only says 'D' or "C' which is qualitative not quantitative and easier to deal with in production (I would guess). No commitment as to how much 'D' or how much 'C'. The gauge I have here has been out of a car for many years and the needle still returns almost to zero. Wow. I do not know how my '55 gauge works nor my '64 Dart. Problem with this '64 Chrysler design is that a high level of current must be passed from the engine compartment (through the plug thingy we '60/'70s owners all love so much) and back again. So, what GM did for awhile was measure the voltage drop across an appropriate piece (oops, slight interruption in meassaging to go outside and watch an Apache Longbow leave the airport headed east. Guess the pilots love our red rocks, they come here so often) of wiring in the harness that they can accurately control the resistance of. The GM gauges I am familiar with were 'D' or 'C' marked. Also a system used by International trucks. I think my '80 Horizon works this way also, but I may be remembering wrong. There will be a voltage drop, a measurable voltage, across any conductor that is carrying current and this can be a valuable observation to make when checking out an electrical problem. Warren Anderson Sedona,AZ [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: Chrysler300-digest@xxxxxxxxxxxxxxx Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/