Aging questions like this are tough, especially when you're in a national forum, where everybody's deer look a little different. If those bucks were in western MT, the top two are 3 1/2 and the bottom one is 4 1/2. I'd give those estimates with 90% certainty. That said, I don't know much about KS bucks, since we moved away from there when I was 12.

You've got some good looking tracking soils in those pictures, so let me make anoff-the-wallsuggestion. Measure the tracks. Don't guesstimate, get a ruler and measure their width right down to the 16th of an inch. (You could also take length, but I've always chosen width. Be sure to measure only unsplayed tracks.) Measure enough tracks and you'll start to see the sense in it. Lots of people will object that this won't work, but I've been doing it in my deer areas for a few years now. I have yet to see the "doe with huge feet" or the "big buck with little feet" or any of the other objections people raise. In my area a 2 1/2 y.o. buck will go 2" wide, a 3 1/2 y.o. 2 1/4" wide, and 4 1/2 y.o. about 2 3/8" wide. (These will vary by +/- 1/8", so past 3 1/2 years oldthe measures may start to overlap. The biggest doe I ever measured was 2 1/8".)The widest track I have ever seen was 2 5/8" wide - this in an area where bucks do occasionally die of old age and 5 1/2 to 7 1/2 y.o. animals are to be seen.