Hello Kwoods. I see you are still waiting for a response so I will give you what I know.
1. You might want to search the Modern version of YTMag. There have been many many posts on this topic over the years.
2. On a 20 series tractor, e.g. my 4320, you want draft/load control in "D" when you do this. You will have to translate this for a 40 series.
3. You can get JD Parts or to the this website:
They make the parts for this repair and some feel they have a better sealing system. I bet if you called them they would also be helpful.
4. As a minimum I would replace the transmission housing bushings, seals and load shaft.
5. There is also a bushing, two, in the wishbone, it is a bear to get out so I tend to replace them only if I can convince myself there is a lot of wear. Or better yet, check specifications. Others may want to comment.
6. When taking the seals out of the transmission housing make sure your pounding on the seals and not the transmission housing. I like to use an old load shaft ground so I can easily feel the lip where the seal meets the housing.
7. The bushing in the transmission housing has an inner taper to it. Pay attention.
8. Chill any bushing you are installing. I stick them in the freezer for a couple days but if you do the math that does not help much. Maybe dry ice or something colder if you have a source. Again, others may want to comment.
9. I have done this enough I have gotten my self some good seal/bushing driver sets. It's hard on sockets to use them in this manner. Ha, Ha.
10. You may want to warm your O-ring to install it. I have seen 160F suggested.
11. There are special washers of varying thickness to put between the transmission housing and the wishbone. This is really important to take as much side play out as possible, a major cause of seal failure. Tim S is the expert on this. Tim S may want to comment.
12. Lubricate the Load Control shaft and seals as you put them back in.
13. Make sure the shaft engages the internal load control arm properly, this is why you need the load/draft control lever in "D".
That's what I can think of. Please, others feel free to comment even if you disagree with any of my comments.