Any ideas on how hard it is to convert a sickle bar mower to belt drive

[flusher]

Then of course one must transform the rotary motion of the driven shaft to reciprocal motion to drive the sickle.

I vote for selling the pitman drive mower and buying a pitmanless model.
Unless, of course, the OP has nothing better to do and wants a challenge.

Yep, you can't get away from having a crank (pitman) somewhere in the design. The crank on my MF31 is called a DynaBalance design and is fairly complicated. You could rig up a simple short shaft crank to change from rotary to reciprocating motion on that mower with the long pitman. Just makes the job a little more difficult.

 

[Pooh_Bear]

If you weren't so far away I have an old Dearborn 14-67 SBM that needs lots of TLC and a few parts. I've been trying to get $50 for it. I could even be talked down a little from that. (I got $35 in it.)

Pooh Bear

 

[Kioti Tom]

What's the reason for using a sickle bar mower nowadays? It seems slightly outdated unless you've got a small patch of hay you're going to cut. I see a perfectly good brush hog in the background there, much simpler and less maintenance, seems to me.

With the pitman arm you can't do banks well and ditches, forget it. With the belt drive (eg. MF 41), you can cut almost vertically up and at a pretty good angle down in the ditch. Unless you have one of those articulating arm setups with a brush hog, ditches would be hard to do and forget roadside banks. So my vote is for the belt drive.. I use one for harvesting goldenrod in the fall. Make good pellets for the stove...