I just got my Kelly controller, and the supplied diagram shows a three wire 0-5 V throttle with a note in italics on how to wire a two wire 0-5K pot throttle. I have the 0-5K pot.
Most I know have 0-5K ohm pot. I was under the understanding of the controller design controlled the throttle design. Not that it was a choice you made.
We have an Altrax in one of our cars and it is not to fussy about the 0-5K Ohm throttle. It works all the way to 6K Ohms.
We have a Kelly in our other car and a spare kelly. We were using 0-5K Ohm throttles on the kelly and were having all kinds of problems. Just a tad over 5k and the controller would cut off. I was ready to adjust the Kelly with a big hammer.
We went with the 0-5V twist grip throttle from Kelly and have not had a problem since. They were way less from Kelly than other sources. We bought extras and have not had to use them yet.