These were removed from a 2009 Duratec R500 but are, I believe, identical to the units fitted to R400 / 420Rs as well. The spring is Caterham's 30% uprated progressive (part number 74076) which gives rates of 110/130/170 across its useable travel. No known issues and in full working order when taken off the car. The damper is Caterham's Bilstein unit as fitted to these 'R' cars.
Looking for £65 the pair for collection, or I can ship at cost on top.