Stealers will normally ask for a chassis number for any part if they had anything about them so they can order the correct part for that vehicle.
I work at a dealer and our parts lads always ask for the chassis number as there may be 2 or 3 slightly different parts even for the same model.
Dealers would not be able to sell you 888 parts as Vauxhall would not release them to the dealer unless you could 'borrow' a chassis number.