Not sure about the exact numbers on our (Interstate) group 31's, but the group 27 Mega Tron Plus is 800 CCA (1000CA) with 150 min RC. We have a dealer account so I put a set in my truck when I got home from the Marine Corps. The set of work horses (interstate Ag/industrial line) have been in our IH 886 for over six years now and never had a single problem; even in the Wisconsin winters...

 

I straight up run dual cheapo Walmart yellow batteries. Each is like 700 cca. Works great so far. Costs $62.88 a piece. I've got new battery terminals on there with a lot of NCP-2, and I clean any corrosion as soon as I see it.

 

Thanks for the info on the GRP31's. I just might go that route when mine die. Looks like original batteries, but I bought the truck with over 100k and have no idea if they were changed by the previous owner. I have put approx. 60k miles on them, starting in all weather and all temperatures. Had to get a jump once after running a rear winch lift for several cycles without the truck running. oops.

 

Try this link for Optima's they seem to have a lot of info charts along with prices. They show free shipping to lower 48 states, but I'm sure the price of shipping is figured into the total. Still has some good info about them.

http://www.1st-optima-batteries.com/

Tony

 

Just Replaced them with the same thing that was in there for years,
Interstate MTP 24's 85 Month Batteries, AWESOME Price.