A long while back I posted on installing Group 31's in my truck. It has worked out well,but a few things to check on yours. Watch for the tops of the batt terminals rubbing on the underside of the hood. I ended up grinding mine down a bit to stop this. You will see them wearing on the hood insulation first,and eventually they will wear threw.
To install them I had to cut and mod the battery tray as well,and make a new top retainer,by cutting the old one and widening it. Now that they are in,i'll never go back. Way more cranking power,and reserve power. I left the dome lamps on all weekend (3 days),and it fired up at below freezing,something the stock batteries would never do.
I have never had any luck with Exide either. We sold them for 6 years and had nothing but problems. We have since gone to Interstate as our supplier,and the problems dissapeared. Plus the customer service and support is second to none.
I also added a Leece-Neville 140 amp alternator which blows away the stock unit. It has been about a year and a half now and no problems as of yet.