First $20 and a beer gets it. Will bring it on the next AAT run so no need to ship.
Here is a link to it and what it does: https://www.dirtyparts.com/store/detail ... pid-161838

I have one of these in my FJ currently and it gives about 0.6 - 0.7 volts extra out of the ALT. This is required if you are running an AGM battery.