I was going to replace my 151R battery with a 51R because of what I had thought was a parasitic drain but turned out to be a poor excuse for a battery. I removed the tray and discovered there was enough room for a much larger battery at almost 1/3 the cost. I built a battery tray out of angle iron (7" x 8") and bought a Walmart #26 Value battery for $60 including taxes. The 26 has 650 cranking amps at 32 degrees. Subtract $60 from the $160 (with taxes) the 51R costs ($100) and that's how much you can stick into getting that tray made and installed. The positive battery fixture is made from a positive clamp with a threaded bolt extending vertically and a positive post with a threaded bolt. they are connected by 3 nuts welded together to create a 3/4" nut. There's probably a nut already made which will work at a hardware store for purchase though.