Some interesting comments made. I have both the yellow top and blue top big crankers in a 40 series cruiser both have 2006 date on them and they have been shown no mercy since 2010 when i took over ownership.They are still goin strong.

Were the gun battery in the day but like previously posted they went off .the boil so to speak when outsourced to Mexico I have read some where that production has since moved back to the good ole US of A.

I will be gettin either the yellow or blue top as a cranker in the near future I can only go on my experiences with them for better or worse.

For my 10 cents worth I say go the D31A or D31M.