Distributor difference

One’s an early 239 (or 256?) the other later one with the later model cam.

Explained here

 
The 256CI (EBY) was a continuation of the SMALL CAM 239/256/272CI.

You will have to ID what engine you have.

It sounds like your engine is an 239CI EBU and the previous owner also sourced an EBV DIST for possible upgrade.
 
I should have been taking notes but IIRC when I swapped in the '57 distributor I had to remove it's gear because it had 14 teeth and the EBU distributor had 13.
 
The 14T may also be a 1957/ DUAL ADVANCE DIST used to convert from LOAD-O-MATIC to later DUAL ADVANCE IGN.

There will be ID NOS on the DIST BOWL(s). Post them if you can.
 
The oil pump drive in another thing, Some later ones will but most don't. They changed from a slot & tang drive to a more modern hex shaft type drive. Folks change the oil pump if they want the late type drive and distributor. The cam can be involved if a person wants the late gear on the distributor otherwise, put the early gear on the late distributor but make sure it is in a timing friendly position.
 
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I have two 1954 distributors; one has 14 teeth and the other one has 13 teeth ( shaft gear ). Why ?
The 14 tooth gear number is 12127; the 13 tooth is temporarily installed .
To match the number of teeth on two different styles of camshaft.
Fyi, 12127 is the base portion of the ID number for virtually any distributor part.


A few example photos to help ID Y-block distributors.
1. '54 to '56. Loadomatic, vacuum canister operated timing advance only
2. '57 to '59. centrifugal timing advance w/ vacuum canister & round timing advance plate
3. '59 to '64. centrifugal timing advance w/ vacuum canister
4.. Loadomatic distributors usually have an ID tag riveted to the side. This one is FDT 12127-B1
5. '57+ distributors have their ID cast into the side
 

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  • 59+ dist pivot plate, curved adv arm.jpg
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  • FEJ-A2 '57 dist, circle.jpg
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