After checking the grounds, I would suggest you buy the biggest battery that will fit in the tray without interfering with hood closure, tiedowns, or cable reach. Also, might be a good time to replace cables with heaviest gauge you can find. And check the electrolyte level occasionally, I've seen many a weak battery that had levels below the full level. Liquid should look cupped, not flat when looking straight down the fill opening. Always good to cover the basics.