[ajmac]

Does look expensive.
If you look, the made up chassis is much narrower than a UC so the T16 rear axle would only be good for the diff and brake bands. Also if you look at the distance from drive sprocket to idler there is either simple skids to guide the track or a series of small wheels, can't be normal UC road wheels, perhaps a series of rack return rollers.
T16s are what...180ish tracks links per side. I read the advert as enough track for three assemblies, i.e one and a half carriers worth, but looking at the indoors and outside photos there looks to be at least enough for two carriers.

NB: I think I was given the heads up about these tracks last year, there is a saw mill in Wiltshire who have a similar setup which they use to move timber into the building, with the openable fence panel wall etc... I was also told that the mill owner 'knew they were very valuable', possibly the same place.