Don,
Per the JD parts website catalog 2979, Grid C6, Section 10, Page 44, there are two blades for a 140. A model E0611 (54") for model years 1970 to 1974 and a model E0610 (Model 43 that is 42") for model years 1968-1969 (Yellow) and 1970-1971 (White). This blade is similar to the U043 except that it has a hydraulic cylinder for lifting.
A model E0610 will probably be difficult to find. I was searching for a 48" blade for my 322, but they were between $500-$600 plus shipping.
I had put a U043H blade on my 317 and was impressed with it's capability. This blade was designed for 200 series tractors without hydraulic lift. All I did was to install a support frame and hydraulic cylinder in the front of the tractor.
I live near Atlanta, GA. and do not have much snow to push. What I use it for is to clear woods and push concrete otherwise known as Georgia red clay.
I really like the narrower blade since I push dirt, rocks, and trees. My 317 has fluid in the tires, 250 # of suitcase weights on the rear, and bar lug tires. I run out of traction not power so a wider blade would be a disadvantage for me.
Another advantage of a custom design is that I built in blade height adjustments. A factory blade has only one setting. I have 12 different depth settings. This is necessary if you want to cut a trench or are pushing light soil.
I just completed adding a U043H to my 322 yesterday. I have about $350 in the setup.
Here are a few pictures.
I need to do a little grinding on the front angle irons.
George of Buford