Grant: As short and FAT as I am, the D2's can be pretty uncomfortable for me as well. On some of the topseat versions here, I raise the seat cushion 8" inches for more leg room!
Others have put spacers and raised the seat base on the orchard machines too. 
Good luck on your adjustments, it can be a pain to remove the tank, etc. Don't forget to adjust the brakes while the hood is off too.
I have a nice top seat tractor coming here in a couple of weeks if you give up on yours. JM

        I've been driving my D2 5U the past couple of days discing also, it pulls this rig in 4th gear easily, but yes, those D2 cockpits are cramped, I have the seat as far back as it will go. I fitted new General Gear steering clutch plates to this tractor 10 years ago, plus new brakes, and it is sweet to drive.

The 22 tailseat tractor that is on the ranch has a length of 6 by 6 under the seat. Raising it up and back. I think that I will do that to this D2, since it is no fun the way it is. I actually have never sat in the tail-seat 22. I think I will check it out.

I just spent the afternoon watching "Squatch253" videos and learned a lot. I am going to try to get the main clutch over-center adjustment better. It takes both arms to get it to snap in and a real hard push to dis-engage it. I originally thought that it was an oil clutch, but after looking at the manual and Squatch,s video, I think it is a conventional clutch.
My older D2 3J top seat is way more comfortable to run (but not running anymore) and I uncovered it a few days ago and worked the clutch lever and it snaps in and out with reasonable pull and push.
At least this 5U has good power for pulling logs and stumps.

Mike Meyer, are the General Gear clutch plates the newer, thinner style that are never supposed to seize? I just recently saw an add for the new style and they sound interesting.

Grant.

Yes Grant, they are the bimetallic type, they are nice, though you need more plates to fill the clutch pack, as the new plates are thinner, John Parks will have the number needed.
Mike

My brother took the seat risers from our dads RD4 that had a winch on it and put them on his D4 G model since my brother is 6 foot 3 inchs. At 5 10 I found the extra leg room nice. Since the tailseat is the only Cat running right now, I will try to make it more user friendly.

I wont give up on it even if Juiceman covets it. Ha Ha. Grant.