Carts Unlimted use to have a some Yewey's but I did not see them when I just looked. I only saw the Summit II's. You can check with him.
Here is some from eBay.
https://www.ebay.com/itm/36-Volt-18A...gAAOSw-Ihdib4~ You will want the 15-18 amp range. The 5 amp are too small.