Had to upgrade my battery after 2.5 years on Group 48 Replacement Battery - Rennlist Discussion Forums
I prefer AGM (Absorbed Glass Mat) Gel type batteries
I replaced an Interstate MTP-H7 With a Braille endurance series 7548 AGM battery - direct replacement.
Braille AGM B7548 battery group 48
BCI Group: [?]Group 48
Length:10.9" (277mm)
Width:6.8" (173mm)
Height (without posts):7.5" (191mm)
http://www.braillebattery.com/
http://www.braillebattery.com/index.php/braille/product_series/endurance_series
Battery sizes that fit 996 (group 49 will probably need a nut under the last, unthreaded, hole in the tray)
Group Interstate number Dimensions L x W x H Posts
48 MTP-H6 10-15/16 x 6-7/8 x 7-1/5 Top
94R MTP-H7 12-3/8 x 6-7/8 x 7-1/5 Top
49 MTP-H8 13-15/16 x 6-7/8 x 7-1/5 Top