Model A 28/29 to 30/31 what is different?

This may sound like a silly question but what is the difference between a 28/29 and 30/31 model a fords?

 

The cowl. The belt line. The canvas line on the roof (coupes and two door sedans).

Just look at a bunch of pictures and you will soon figure it out for yourself.

 

Thankyou just got a bunch of parts and didn't know how to ID the cowl

 

http://www.jalopyjournal.com/forum/showthread.php?t=429137

 

Well, as best I can describe it, the '28-9 cowls have a check mark looking design in them. Kind of a carry over from the "T"s that had a smaller yet similar check in the cowl sides.

 

There are 28-29 Fordors that use a 30-31 style cowl but retain the 28-29 firewall except it is 3-piece rather than 2-piece like the Pickup, Coupe, Roadster and Tudors.

The firewall on 30-31 is a one-piece unit that unbolts. The fuel tank is behind it.
The upper portion of the firewall on 28-29s is the front wall of the fuel tank.

The gas cap and radiator caps on 28-29s are threaded and the same size but the gas cap is vented.
The gas cap is bigger than the radiator cap on 30-31s and they mount with ears like modern cars.

 

good visual of a '30/'31 type cowl profile...

 

'28/'29 cowl profile (from elsewhere on the HAMB)

 

stock grille shells and firewalls are fairly commonly changed on hotrods and I feel like the cowl is the best visual indication of the difference

 

Cheers you guys are good.