I had this problem on our 77 Chris Craft Lancer, 350 SBC AQ280 outdrive. 1st you need find and download a factory repair manual, I also found part number listings and diagram, for the AQ280 there were 4 of them, upper gear box, intermediate housing, lower gear housing, and connecting components. these are good so you can see how everything goes together and what parts to order. Now I don't know if this was the right thing to do, but It worked in my case. 1st I searched many websites, some said to use a slide hammer others were like what Fishermark describes. I didn't like those ideas because of the fear of hurting the upper gear box . We were doing a total repower. So we removed the upper gear box housing from the Clamping ring housing, once the gear box was removed, I could then remove 1 socket head cap screw and the clamping ring housing was removed. Now you could use a slide hammer to break the yoke loose from the PDS shaft. We didn't do that till later, after we remove the PDS housing from the boat w/the yoke still attached. I periodically squirted PB Blaster back in the cavity where the yoke was stuck to the shaft. When we were ready to use the slide hammer, the yoke fell off while attaching it. You will need the upper gear box diagram so you can see which seals to replace for assembly. . IIR, there is a special washer in the clamping ring housing that you do not want to loose and hope it is still in good shape. If you replace that you will have to set up the bearing preload or something like that. Hope this helps. Ken
