I have all 4 of McCulloch's electric start models. 3-10E,5-10E,10-10E & Super 10-10E Produced June 1966 to May 1970.The 3-10,10-10 & Super 10-10 are 3.3 cube/54cc,the 5-10 is 4.3 cube/70.5cc.All are fairly scarce,not a lot were sold even though the idea was revolutionary at the time. 2 have missing battery packs,1 has pack but needs rebuilt.I've heard that Interstate Batteries,Batteries+Bulbs & at least 1 other business can rebuild them for around $50-60 or so.