The loop on the front of the body is the bit that gets broken off when the dodgy b*stards we know so well do body swaps on these. Bodies fit quite tight even without it, but if there is any suspicion of interference like marking to the tabs on the back of the chassis, it's always worth seeing if the body comes off without too much effort. If it does, it'a a fake. Blue interiors are usually seen on Y22 prepro and trials. Oddly, this base is fully numbered and dated.
This one is also un riveted, and has an un-numbered and undated (19 ) base.
Has taken over a month from day of sale for these to arrive from Vectis