You can use this link here: Service Information for two-Cylinder John Deere Tractors
After clicking on the above link scroll down and click on 2006 Aftermarket Equipment for tractors. It's an Adobe Reader and will download in a couple minutes. Beginning on page 55 there is info on Power Blocks. There are other neat products and add ons shown in old advertisements on this Adobe Reader. Take a moment and look at each page.
On the jd2cylservice.com site there's some additional helpful info for 2 cylinder tractors.
Hope this info helps