NIR Mk2 coaches and 80 Class Intermediate Trailer Conversions

[PaulMac]

Hi, I have been researching the NIR mark 2b/c stock and 80 class DEMU centre cars with a view to modelling them from Lima coaches I have stored away.  With regard to the hauled stock, please could anyone tell me whether any of the Mark 2c coaches NIR had were fitted with the Mk2d, e, f toilet windows or if they all had the Mk2b type toilet windows?  I know the early Mk2c stock had larger roof vents than the later type which had similar Roe Vac roof vents to the Mk2 air conditioned stock.

On the subject of 80 class intermediate trailers, the ones that interest me are the conversions from hauled stock.  I have checked two sources of reference for these and differing information is provided about the interior layouts.  The Harris book documenting Mk2 stock states that 774, 776 and 779 all had 62 seats and 2 toilets, the same book states that 778 and 780 had 76 seats and no toilets.  The contradictory information comes from a Platform 5 handbook from 2008 that says all of these had 74 seats and 1 toilet, I'm not sure which is the case.  Another query I have is related to driving trailer 754 which I know was converted from push-pull BDTS 811, as built, this would have had 31 seats with toilet, the Platform 5 book says 75 seats and a toilet, if this last vehicle did have 75 seats, that would have been almost a complete rebuild from a brake coach into a full saloon, was 754 so heavily rebuilt?