Another difference is the belt between the tiller and the right angle drive is 3/8" on a model 1 and 1/2" on a 1A. It looks like you can add one or two extensions on a model 1. The owners manual says that in hard conditions (whatever that means) at full depth not to use extensions. You can even add the covers for the extensions if you can find them. I just picked up a model 1 and the tine shaft is 1 1/4" and has holes in the outer ends to add tines on. You will need the lift bar for the tractor if you don't have it and I guess they're different for a tiller versus other implements, the hole in the end needs to be vertical for the lift chain on the tiller.
RAYAR wrote:Both idlers with no spring tension to likely help keep slop out of the long belt to the rear angle drive gear box
That's interesting, I saw that too. I wonder how difficult it would be to add a spring loaded idler somewhere along the length of the drive belt to keep things snug and not flapping so much like they seem to do on a mower deck.