Well, I'd have to say if it lists the 120 then thats the FEL they did the engineering tests on. From what I'm told Koyker does destructive testing a unit when they design it. That means they use a "ginnea pig" tractor and torture it after they design and install their designed FEL.
I would call them direct and ask but they may not warranty a non applicable model installed. You have to look at the big picture. Koyker does a real good engineering job and their units are strong. I loaded my bucket with way more than I thought was safe for a test and I still could add more. Not again for me, 2 smaller scoops safe is better than 1 overloaded unsafe bucket. Breaking stuff or worse yet, flipping is no fun.
There are other after market FELs also, Great Bend, Woods, are a couple that come to mind. I assume you have checked on a Kubota brand FEL?