could they have not just cut the door open a bit bigger on the transmitter truck one? and thats why it doesnt have the 2 flashing lights above the door?
Well, that's always possible. From memory the Transmitter Truck pod seemed somehow sparse so always assumed it was one thrown together quickly purely for that episode.
I remember seeing the Mole scrape the underside of the opening too, but noticed later there was a bit more headroom!!