I've been running my 6 volt starter on 12 volts for 10 years and 45000 miles. I had to put a set of brushes in it at about 25000 miles of 12 volt (changed the springs and bushings at the same time, all available over the counter at my FLAPS). No telling how many miles the starter had while operating on 6 volts before I bought my truck.
I'm careful not to spin it too long, but my truck starts within 2 turns of the crankshaft in any condition except turn it off hot and let it sit for 20+- minutes. Then it might take 10 turns.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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