My battery (Group 35, regular old lead acid battery from The Walmart) died a couple of weeks ago. It was 9.5 yrs old so I can't complain. Wanted to drop some weight so I was looking at the Antigravity 51R-30-RS initially, but after talking to Pegasus Racing and an engineer at Braille I ended up getting a Braille Green-Lite G30 and an Optimate lithium charger/tender straight from Braille. In order to install this, you WILL need to get an adjustable battery hold down as the factory stamped steel angle iron piece will short out across the terminals since the battery is so much smaller. It will also short out because Braille uses small, threaded, recessed terminal blocks on the top front corners of the battery which it would be laying directly on. The actual battery terminal posts bolt into these blocks. Note- the slightly wider one with a smooth ring around it about halfway up is for the positive. It has a knurled areas above & below this smooth ring.
I got a Diehard hold down (# 45164) from Advance Auto parts. It's $10 for what are clearly two 89¢ pieces of plastic that are made in China, but it gets the job done. I strongly recommend setting the width to snugly fit across the battery (left to right direction, not front to back) then use electrical tape or a couple of zip ties to secure the 2 halves of the bracket together. You will also need 2 medium sized washers with holes slightly bigger than the j bolts as the holes in the bracket are almost the same diameter as the nuts. I was worried the nuts might start pulling through over time. Push the battery all the way rearward centered in the battery tray. Then position the bracket somewhere over the center of the battery (front to back dimension) running left to right. Swear repeatedly while trying to tighten the nuts as the j bolts keep falling out of their anchor holes in the edges of the tray. At some point you will get it.
Connect the positive terminal, then the negative. Go start car. Bask in your success, then go drink a beer.
I got a Diehard hold down (# 45164) from Advance Auto parts. It's $10 for what are clearly two 89¢ pieces of plastic that are made in China, but it gets the job done. I strongly recommend setting the width to snugly fit across the battery (left to right direction, not front to back) then use electrical tape or a couple of zip ties to secure the 2 halves of the bracket together. You will also need 2 medium sized washers with holes slightly bigger than the j bolts as the holes in the bracket are almost the same diameter as the nuts. I was worried the nuts might start pulling through over time. Push the battery all the way rearward centered in the battery tray. Then position the bracket somewhere over the center of the battery (front to back dimension) running left to right. Swear repeatedly while trying to tighten the nuts as the j bolts keep falling out of their anchor holes in the edges of the tray. At some point you will get it.
Connect the positive terminal, then the negative. Go start car. Bask in your success, then go drink a beer.
Looking at it on the web did not engender more confidence. 
