I know this has been discussed before but I need some clarification. What is the difference between the d34m,31m and 34m. I believe I have even seen a d31m? Are the "d" combination batteries with high cranking amps as well as a deep cycle? I am looking for a quality and have had good luck with the optimas but just want to make sure I am buying the correct one for the new boat. The cost of a quality battery is worth the hassle of not having to worry about it to me. <BR> <BR>Also, <BR>Does anybody have any opinions on more cost effective alternatives?

I just looked that info up on their website, it's detailed there.

Thanks pwork. It looks like i need to go with the d31m or d34m. <BR> <BR>Does anybody know of any other batteries that are worth the $ and compare to the optimas?

check out Kinetik. <BR> <BR><a href="http://kinetikaudio.com/hc2000.asp" target="_blank">http://kinetikaudio.com/hc2000.asp</a> <BR> <BR>You can pick up an HC2000 off of ebay for around 230 after shipping and it is almost as powerful as 2 optimas. <BR>2250 amps / 102 ah

check out batterystuff.com they offer several different AGM brands. I used the MK 110 ah on my last boat and it held up well to some serious stereo drain abuse. Optimas look nice but you can get a much better AH to $$$ battery out there.