Tudor Sedan Top Wood Kit Questions

[pkhammer]

I came into possession of this top wood kit which I think is missing a couple of pieces but my main question is this; all the parts are marked "TD 30-31" EXCEPT the four pieces that run front to back that receive the ends of the cross-bows. Those pieces are marked "TD 28-29". This leads me to believe that this has some mixed and matched parts. Would those parts be the same as 30-31 or are they different?
Thanks in advance.