There is a T262986 cast on the bottom of the steering box and T265999 cast on the cover bolted onto the side of the box that I removed from my car.
That number jives with Don's info and with the other pictures I have seen.
It is clear that the T and TA boxes are not the same size, I am not clear on whether a TA box will bolt onto the scout car frame, whether the mounting flanges are different. I would not mind making a bracket or replacing a piece of armor with steel clearanced to fit over the bigger box.