It's not too bad. The radiator needs to come out to get the steering disconnected. Then its just a matter of jacking it up and removing the old axle and putting in the wide one. Bolt the steering box back on top, close it up.

I don't think it can be done without removing the radiator, as the cap on the top of the steering box needs to come off to remove the bolt that holds it on the steering post, and I just don't think there is room to do it without getting stuff out of the way. While it is Out, I'd replace the quad o-ring at the bottom of the steering box, and the one on the cover as well. The bottom is easy to do while it is apart, and only costs a few bucks.

How far are you willing to travel for one. I saw a 1655 diesel WF in an ad in the Michigan Farm trader that just came. I don't know the owner, price or condition, but it looked nice in the picture. I can get you a phone number if you are interested.