go to a catapiler/ fabco dealer
get a battery of comparable size to original
done
they are built by exide to catapilers specs.
they last about 4-6 years and cost 50 to 80 bucks depending on size
they are built to last in off road construction equipment, high vibration high shock, hard use. they have no or very little suspension most are diesel. so you can imagine what the battery must endure.
when pro 4x4 drivers use the free optimas (sponsership) for everything but
the race truck, something is amiss.