My pump drive is as close to worn out as it gets.  I think I can buy a new coupling and have machine shop remove and install it but wanted to post here first in case someone has a spare laying around. This is on a 7U-D4 with a 44 front pump. I’ll attach pictures of my drive so you can see the style it is. There are a few different ones. Thank you Robert      

That shaft can be repaired fairly easily.
My method to do that, is to purchase a new coupling, Hub-City 0332-00348, best to confirm that part number, cut off the old coupling section, then turn down the shaft to a couple thousands larger than the ID of the new coupling, press on the new coupling until the correct length and weld in place. if you can't do it, it should be an easy job for a machinist.
 What condition is the input shaft?

I've done a few in the past. Made some blanks and had a gear company put the internal splines in them.
Josh, Is that coupling in the picture a good match? I can't remember if there was one available off the shelf that matched the dimensions but I didn't have internet when I had mine made.
Not hard to change out if you have a lathe and a welder.

Josh, thanks for the part number, ill look into that coupling. I just had to do the same for a Be-Ge pump shaft that was worn out. Figured thats what i was going to have to do. As for the imput shaft... oh its not perfect but better than the coupling. Should outlast me. Thanks Again for the help. Robert

That coupling is the proper match for that spline, also the same as the winch and PTO input shaft spline on the D2. The coupling is long enough to press on to the cut down old shaft, which makes it very easy to get proper alignment, or it could be cut in half to make two couplings.

That coupling has more meat on it than the one I replaced on the 416 backhoe that used to be here! JM