TA-TB v TC chassis/body frames

[bloodysalmon]

I appear to have a pair of TA/TB chassis/body frames that I can sell on. I also have a pair of TC ones and I can see where the difference is ... about 1" to 1.5" per side width .
Now prior to advertising them, I wish to confirm what the subtle difference is between the TA chassis/body frames are up to chassis number 1090, compared to that of TA chassis number from 1091 and the TB?
Looking on the Moss site you can clearly recognise there is a difference (knowing the TA is narrower of course) as each are cataloged ... anyone know for sure how to differentiate?