I happened to look today and the battery in my '35 1.5 ton is 7 years old.  I can't get any other 6-volt batteries on the  farm to last more than three years (and I think this is was a cheap Farm and Fleet battery when I bought it), but this thing just keeps going.  I do drive it everyday, so it stays up, I guess.  I use some of those tractors each day (2 sixes tied together) and they don't last like this thing.  I've always sworn that generators were easier on batteries but I was still kind of surprised at it's age.  It's sure to leave me in the hay field when it is 105 this summer! Are you finding that batteries in your old stuff are lasting like this one has?  

Now that I think of it, I'm pretty sure the 6-volt battery in the '54 6400 grain truck was a year older and it's still going.  I did switch it over to a 6 volt alternator when the regulator died years back, but that hasn't stopped it.  I remember buying 6-volt batteries like candy when I was a kid but these are surprising me.