The Hadcock Arm is a GH220ss,,it is a gimbal arm,not a unipivot like the GH228..They don't make the GH220 now..Available secondhand on Ebay sometimes,,luckily not that collectible,,because everyone associates the name Hadcock with unipivots the GH220 can be a bit of a bargain,,I have saw them go for £200 or so..The unipivots are about £700 new which I think are over priced..Overpriced because of delicacy of build,,not because of sound quality..
Hadcocks sound delicate and airy in general,just for some reason not so much on this Thorens....Detailed but not a powerful sounding arm,,although the GH220 can still sound tight compared to the blurry 3009,,if used with a fine tipped diamond,,the Hadcock GH220 has an almost surgical sounding treble,,not in an over bearing or bad way,,just very precise,,a touch light in the bass in undamped tube form,,better in many ways than the SME 3009 soundwise I reckon,,well I owned both and did a comparison and the Hadcock beat it by miles..A bit fiddly to set up though and very D.I.Y-ish,,the tags will definitely have fell off if the arm is secondhand..George Hadcock used to rewire my arm for me,,he has now sadly passed on..He was a lovely guy..
He made the GH220 for his TD160 b mk2..That is what he told me..The original SS designation meant stainless steel,,the arm tubes were filled with silicone sealant I think it was,,better for medium to low compliance moving magnets and moving coils,,this set up wasn't so bass light in balance..probably about the same mass as a Rega RB arm in that guise I reckon,,a bit above 10 grams,,the black tubes were un-damped aluminium and the effective mass was 5 to 6 grams in that form..Mine is actually an undamped Stainless Steel tube,,hence SS,,I think they are using those in the new 228s..
The GH220ss first came out in the very early 1980s,,about 1981 I think and was only built for a few years..It was reissued for a short period in 1997,,they we sensibly priced during that run also as were the 228s. The first Hadcocks appeared in the mid to late 1960s..Called the Unipoise,,Some straight,some S arm,,the design changed a lot and constantly apparently,,a bit of an eccentric inventor was Old George..Haha!!,,but as I say,,a lovely Man..He phoned me at about 5 AM in the morning once on my opinion on his new damping he had put in my rewired arm tube..He was excited like a kid,,I was woken up and barely knew where I was,,he was brilliant,,Haha!!..He worked in Aircraft design originally,,I think it was for Handley-Page..