It looks like my grandfathers were 36", but they are so deteriorated its hard to tell. We bypassed the chute many yrs ago and rigged up cattle panels and some post to make it work. What we use now is more like 48" and they turn when they want. very aggravating. For my new pens I was leaning towards 31". How high do you make the panel solid coming up from the the bottom? I was thinking around 3' with 2" pipe welded across so the hooves wont get hung up when they jump and come down. I like having slot i can wedge pipe across the "alley/chute" to keep them from backing up. Hope that makes sense.