The older batteries were thicker than the new ones you can buy today. At least this was my experience. Although the battery # was identical, their thickness definitely was not. Both were made by a major manufacturer, too, no "off-brand" crap. The thinner cross-section was not clamped tight by the battery contact finger, which made the new battery jiggle around a bit in it's holder, and the car would dump its memory during a power failure. Ended up putting a little ferrule, snipped from a blue Sta-Con fork, over the battery contact finger. This made good contact, and that particular problem went away.
