I checked tonight and it's actually 4kw and about 3.5 to 1 pulley ratio.
Those load nuts look like they are from a Stenhoj 2 post lift, DS2 is one of their model numbers
https://www.ebay.co.uk/itm/2X-Stenh...560733?hash=item3b11f8605d:g:OPoAAOSwPcBbLOuI
HPC might well have been HPC Gears in Chesterfield, no? They've done me one off weird stuff before with threads for steering racks, etc.
A pain to sort out, if you have a lathe CES have cored bearing stock, cheaper than buying solid bar.
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So does mine but it's not bolted down you only have one set of legs working in compression instead of both sets with the rears in tension. It's not so much the length - they kink and fold up at the base as the gussets are small so they don't block car doors.