I have a LNIB William Optics Crayford focuser that was used only twice on my CR 150 HD. Replacing the stock focuser is probably the best upgrade you can make to any of the Synta 5" or 6" OTAs. The focuser is built like a tank out of black anodized, machined aluminum. The focuser rotates 360 degrees which makes it great for astrophotography or use on a GEM which can rotate the tube to awkward positions.
Thank you for looking.