Yep, Land Pride PD35. I am a weekend warrior, and one weekend I spent more than a day trying to put in a few 18" holes.
Before I went home I put 40 gallons of water in 2 that I could not get down much more than two feet. During the week I made a stop by the local John Deere - Land Pride dealer and ordered the down force kit. With a limited amount of time to get things done, I just don't have the time to fool with a few holes most of a weekend. Finished the holes the next weekend without the down force kit, (3 week delivery time) but from then on, I have been able to drill a hole when and where I want to.
Oh, don't know about anyone else, but I learned the hard way that you need to put the down force kit on while the PHD is on the tractor.
I installed mine while it was hanging on my PHD stand, and while most of everything was ok, I did have to re-adjust the position of the hydraulic before I could even get the PHD hooked up.
One last thing, if I remember right, the down force kit was about $550 and worth every penny.
Ultrarunner, how much did you have to pay for yours? Just wondering.