It isn't a GM-8, but thanks to a lot of time and TLC, it's a pretty good mount, better than a new CG-5 because of my modifications, IMHO.
I've listed the positives and negatives below:
-- Ball bearing model
-- Aluminum legs replaced with wooden legs
-- Two-tiered accessory tray
-- Jeff DeTray re-greasing and deburring done
-- Polar scope
-- Custom encoder hardware (mine allow the use of the polar scope, unlike third party suppliers
-- 16 lb counter weight (Stock 11 pound Celestron weight with 5 pound Olympic barbell weight attached with allen head screws ? it's removable.)
-- Motor gear reducers shimmed to reduce backlash
-- Dual drives and controller from Celestron with brass gears and clutches
-- Hand controller tapped to allow use of an autoguider, such as a Quickcam guider
-- I have a website documenting the mods I've done to this mount with an Excel characteristization of periodic error. Email me and I'll send you an URL.
? This is an aluminum body mount. It can carry a lot of weight for visual use (Celestron sells it with 9.25 SCT and a 6-inch reflector, but if you plan to do imaging, all these will overload this mount or any CG-5. Stick to C8 or small refractor, despite what Celestron says.
-- There's no periodic error correction. If you're going to autoguide, then this isn't an insurmountable problem, but it is a irritation.
-- There's still more backlash in DEC than I'd like which makes autoguiding difficult. Evidently, this is a characteristic of the CG-5. As long as you accurately polar align, it's not a problem.
-- minor scratches from use.
-- The OTA's pictured are not included. Neither is the DSC computer.
$500 or best offer.