WCFB Air Horn Choke Differences?

[Beemon]

So I've been admittedly looking for another WCFB carb, and I've seen a few pop up. The most recent one I've seen has the same accelerator rod (straight instead of L shaped) but the airhorn where the choke bolts to is different. On mine, it's an upside down T, but this model has the choke mounted higher up. Everything else matches up. There's a hole in the choke plate, base is the same, the switch is there.. Looks like the secondary throttle return spring is missing, but I know where to get another. Just curious about this difference. Would I be able to put a 55 air horn on this 56 carb? Pics for reference:

 

What the for sale model looks like:

 

What mine looks like:

 

What are the differences if any? Both my carb and this one for sale have the 2347S tags on them.

 

Throttle arm for comparison:

Edited December 9, 2017 by Beemon (see edit history)

[Fr. Buick]

As far as I understand,  the WCFB grew shorter each year to allow for a lower and lowerhood.   You will want to be sure of air cleaner fittment and hood clearance.

[old-tank]

On 12/9/2017 at 9:25 AM, Fr. Buick said:

As far as I understand,  the WCFB grew shorter each year to allow for a lower and lowerhood.   You will want to be sure of air cleaner fittment and hood clearance.

Deeper differences too:  the throttle plates and associated are larger in 55 then 54 for more cfm.