THE FIELD COILS ARE LIGHTER, BY USEING A RESISTER FROME A 57FORD DASH I USE A 6VOLT FUEL GAUGE, AND TEMP GAUGE WORKS IF YOU FIND A 6VOLT TEMP SENDER THAT WORKS(MOST DID NOT LAST WITH 6 VOLT

THE FIELD COILS ARE LIGHTER, BY USEING A RESISTER FROME A 57FORD DASH I USE A 6VOLT FUEL GAUGE, AND TEMP GAUGE WORKS IF YOU FIND A 6VOLT TEMP SENDER THAT WORKS(MOST DID NOT LAST WITH 6 VOLT

The parts book shows different part numbers for the field coils between the 6 volt and 12 volt starters.  I assume they have different windings. I, too have run my 6 volt starter on 12 volts for years.  The windings must have different size conductors or different number of coils in the windings.  Six volters must have heavier windings, that's why they work well on 12 volts.  The armatures have the same part numbers, six or twelve volts.

John - "The Hoosier Hurricane"

I ran a 6 volt starter on my racing GMC 6 and even kept the 139 tooth starter ring gear with 12-1 engine and never hurt it on 12 volts. Because of bell housing rules needed to convert one of those mini’s.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

I am only talking about the starter I am aware that the gauges lights generator and heater  fan  need to be swapped for a 12 volt conversion. I just saying the 6 volt starter can easily handle 12 volts I can not see a difference in construction . And it seems like people are still using the 6 volt starter with the 12 volt battery. Pete has his 12 volt  starter on the the floor waiting for his 6 volt to quit. So Bogus maybe the wrong word  but I am still looking for the answer of how they differ. I guess it not that important. Too much time on my hands been in the house for two weeks now. 

Bogus is a pretty strong word.  Many of the electrical components in my car are original to the six volt system it was built with.  Converting to 12 volts is not nearly as difficult as some people seem to think.  The horns in my car are even 6 volt.  They sound louder, which is is a good thing when you have drum brakes.  I had my 6 volt generator rebuilt at the same time they did my starter.  It also worked.  I ditched it not because it failed, it couldn't keep with with my electric fan.  I just changed all my 6 volts dash lights out.  After 65 years, some of them gave out as expected.  The only thing that I can see that won't work are the stock fuel and temp gauge.  I changed mine to 12 volts some time ago.

I converted my 1955 Tbird from the 6VOLT system after owning the car for over 5 years (I bought the car in 1962). Then I converted to 12 VOLTS.
 I bought both a 12 VOLT starter and DC generator. I added the generator to the car and put the 12 VOLT starter on my garage floor waiting for the day 
the 6 VOLT starter died. I am still waiting. The 6 VOLT starter spins my 312 much faster than the 6 VOLT turned the 292. My experience YMMV, Pete

Excessive cranking using 12 Volts for a 6 Volt Starter will eventually cause it to overheat and fail.You can use a 6 Volt Starter on 12 Volts until it dies. May last for Years.

  

I am beginning to think this 6 volt 12 volt thing is bogus. I think the 6 volt starter is built so well they said let’s just hit it with 12 volts.  I find the battery cables a different gauge

I have the original six volt starter in my 1955 car now.  My car was converted to a 12 volt system before I purchased it.   I took the starter to a rebuilder to have it rebuilt.  When I did, he told me the 6 volt starter would work just fine.  That was two years ago and I have had no starting problems.  My take on this is it will work until it doesn't.  So far, so good.