(quoted from post at 11:39:38 03/09/09) Not trying to start an argument here, but I've got several B-275 diesels, as well as B414s and a 3414. All with single batteries and all will crank fine, even when it's 0 degrees F outside. Not the greatest starting tractors, but the engines are small enough where it does not need a lot of battery power or dual batteries. Starter can draw 450 amps max. I'll add that the later B-275s with the rotary CAV injection pumps start much better then the early B-275s with the inline, air-governor CAV pumps. I have a small car battery (from a Subaru) in my late-model B-275 and it cranks and starts fine in cold weather. On my early B-275, I have a big single battery - the same as the early Dodge Cummins trucks use - and it too works fine. It needs the bigger battery since, to start that tractor, a lot of cranking needs to be done. NAPA # 7235 is more than enough. It's a 31P type battery.
Considering the age of the tractor, I don't know if it still has original wiring or not. I changed all mine. If your tractor is original, all the battery power from the battery, connects to the rest of the system via the post on the starter relay. So, if the nut on that post is loose, or there is corrosion on those wire terminals, battery power cannot get to the glow plugs, starter switch, etc. That would be the first thing to check.