I checked with Antigravity and their batteries offer much the same as EarthX and in the size recommended for the big V-Twins the Antigravity are less money. I think they are also a better fit in the the existing holder and since they have lugs on all 4 corners it is very adaptable and useful. They even offer a Bluetooth App for your phone that will tell you battery conditions real time and will send you an Alert when the battery is getting ready to go into protective Shutdown Mode. Very cool.
Just ordered one so in a few weeks (back ordered) I should know if it is as easy and works as described. 900 Cranking Amps...
Another impressive part for Antigravity is their Customer Support was prompt when I wanted to talk with a Tech about what it could or could not do. I pointed out that their website said a different battery would work. He said it would not and advised the larger capacity and advised against the Re-Start model battery they offer.
https://antigravitybatteries.com/products/starter-batteries/restart-oem/atx20-hd/
