Many years ago I acquired several cases of unissued Florida license plates from the ’70s that were destined for the dump. In going through them recently, I have discovered that I have some that are of the same year with duplicate numbers. Florida has only one rear plate, so they would not have been struck for a front and rear. The plates are identical with the exception that one is steel and one is aluminum. I know that the “E” indicated a rental car, but they would still not have two plates. I was wondering if some of your readers could advise as to why two identical plates were struck, their rarity or value.
— Dan Sams, Naples, Fla.

I consulted colleagues in the Automobile License Plate Collectors Association, since my knowledge of Florida plates is sketchy. Several members responded, clarifying that “E” signifies a seven — or more — passenger limousine or bus for hire. “64” corresponds to Collier County (county seat East Naples, on the Gulf Coast), and the only known two-plate issues are for heavy trucks, dump trucks, garbage trucks and the like. One respondent noted a slight difference in the stamped “E,” suggesting they were made at separate times. Given that they came with other unissued plates and are made of different materials, perhaps the DMV was testing various techniques and metals.

I am re-doing a 1970 Chevy short bed, step-side, six-cylinder, half-ton pickup and would like to know the size of the original wheels and tires. Also, I would be interested in knowing where I could buy a set of six-cylinder headers for the same truck.
— John J. Brown, Warsaw, Mo.

The original specifications called for G78-15-B bias-belted tubeless tires on 15 x 5-1/2-inch wheels, six studs, 5-1/2-inch circle.The equivalent size in today’s tires is 205/75-15 or 205/70-15. As for the headers, I find Hedman 69310, 69313 and 69316, plus Flowtech 11510FLT, all to fit Chevy sixes of 230, 250 and 292 cid. They’re available at Summit Racing, and probably other outlets.

I have a 1947 Ford (six-volt system) and can’t seem to get the temperature gauge to work properly. The gauge stays on hot until the engine has run around 20 to 30 minutes, then goes to cold where it stays. Do I need two temperature sensors — one single-prong and one dual-prong — for it to work properly?
— Paul Medlen, Lisbon Falls, Me.

I think you need a new single-prong temperature sensor. The King-Seeley gauge used by Ford in the 1940s and 1950s is unusual in that it “parks” at “hot” when the ignition is off (when no current is passing through the system). It is high current at cooler temperatures that moves it down to cold, then increases to mid-range as the coolant heats up. The sensor is not resistive. Instead it has contact points that open and close in proportion to the temperature; the hotter the coolant, the less the contacts stay closed and the lower the current.

The dual-prong sensor you mention is actually a switch. Because the Ford flathead V-8 has essentially two cooling systems, one for each bank but sharing a common radiator, a sensor in one bank could fail to detect overheating in the other bank. That safety switch opens once the temperature in its bank nears boiling, moving the gauge to full “hot” and notifying the driver of a potential problem. The two-sensor system was introduced in late 1941, so your car should have been delivered that way. However, you do not need the two-prong switch in order for your one-prong sensor to work properly (in its own bank). It seems to me that it is staying open too long, then snapping closed for the duration of the journey. The sensors (and switches) are not repairable, but Ford parts dealers (e.g. Dennis Carpenter, C&G Ford Parts) have them.

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