I appreciate all of this but it still does not alleviate the fact that a new Hyperglide bottom sprocket will never clamp down the block on an old freehub body.
At risk of teaching people how to suck eggs, the body on the left is from a new freehub, the splines stop short of the end of the body, to allow the 11t sprockets to fit. Old freehub bodies onlt had the option of a 12t bottom sprocket, so the splines went to the end and 'peirced' the sprocket. On an 11t this would leave insufficient metal under the teeth, the cure is to either use a very very thin washer behind the whole cassette (the wibbly one that normaly separates the 2 loose sprockets works) or to change the bottom sprocket to an old 12t.
I think that the suggestion that you shave the ends of the splines, to effectivly convert the body to Hyperdrive C spec, should be done carefully, by someone who is confident at metal work, and with the knowlege that if you bugger it up you would have had to buy a new freehub body anyway.
Somerset, like 'Heartbeat' with newer cars!
Retro MTB: 1992 Cannondale M1000 Deore XT M730. 1992 Raleigh Dyna Tech Quantum Deore XT.
Retro Road: 1992 Eddy Merckx Corsa Extra Telekom Shimano 600 STI. 1993 Dyna Tech Ti Campagnolo Athena 8 Ergopower.
Modern: 2004 Wilier scandium Ultegra 6600. 2014 Wilier GTR Ultegra 6800.