[brother]

I bought a 1/4" x 1 1/2" coil tension spring from a dealer for $2.00, and was able to install it effortlessly. I slid a 1/4" bolt through the holes to keep the coupling and shaft holes lined up, rotated the coupling assembly 180 degrees so that the head of the bolt was at the exit end topside and tapped the pin in from the bottom side with a long 14" punch until the pin pushed the bolt through the other side (I learned that bolt trick from another web page). The pin fits snug with about 1/4" protruding equally out each end (to balance the weight of the pin). I was so happy when it readily pushed through but snuggly!

I did not have to split the tractor as I had plenty of room … actually, I was able to start the pin by first pushing on it by hand until it stuck in place allowing me to be hands free and was then able to tap on it with a hammer to get it started far enough to start using the punch to drive it home.
I also bought some sheets of 1/16" thick vegetable fiber gasket material so I can make gaskets for the transmission top plate and rear end plate after I drain the transmission oil and put in a new filter.

Again, I am grateful for everybody's help … I am sure I will be leaning on you guys from time to time as issues arise. For example, I am now going to post a new question on a new thread about a problem I am having with a frozen zirk grease fitting.