I have a 1960's 4010 / gasoline. I have owned it for 20 years. It uses one battery - 12 volt - 3ET. I have tried batteries from a local battery retailer, Strongbox from JD, batteries plus, tractor supply etc. No matter whose brand I try, it seems the batteries only last a couple of years. Charging system, cables, etc. all fine. Can a more modern 12 volt battery be used with some sort of custom made battery box? Mine appears to have room for a more square box vs the standard rectangular box. If anyone has done this, or knows of a source for boxes, or has any knowledge, I would appreciate the comments or help.