'62 - '63 T-Bird 390 factory tri power

[scicala]

I may be working on a '63 T-Bird factory tri power on a 390 engine.
For some reason, T-Birds used different front and rear secondary carbs (LIST 2497 and 2498), where as the pass cars used the same carb front and rear (LIST 2437). Both T-Bird and Ford shared the same primary center carb (LIST 2436).
My confusion is that the rear carb on this set up has a choke like the center carb, and a slightly different throttle lever than the front carb.
My gutt feeling is that the rear carb has been modified by adding the choke and different shaft/lever. I don't think They would make this originally with a choke on the center and rear carb only.

Does anyone have knowledge of the different T-Bird secondary carbs, or possibly pictures of the LIST 2497 and 2498 ?

Thanks for any help.

Sal