Proper Distributor for a P20

[medium_jon]

The distributor on my 1950 Plymouth P20 Special Deluxe Club Coupe is an Auto-Lite IAT-4103.

But my service manual and my Motors manual lists these 4 options:

When I tried to search on the Auto-Lite IAT-4103, I was seeing options for a 1939 or 1940 vehicle. 

Questions...

1) should I expect problems, or is this fine?

2) the second photo shows that wire / screw on the far left exposed, should it be tight against the distributor body?

3) It looks like the left side of the base is above that plate. I assume this is the locking plate, but I've not delved in to know. Is that crooked, or to be expected?

[greg g]

What is your engine number?  I have three or four distributors laying about.  One from a p28 engine, one from a 

P15, one from a 54 Dodge, and one from a 52 Plymouth.  All are different part numbers and there are three different designs of body shape and corresponding dist cap shape. That is why it is important to take the number when ordering tune up parts.  I did some research on the various models and found that the chief difference among them was in the degree of advance and at what rpm the advance commenced.  I suspect that this was in relation to changes in compression ratio in newer models.  The difference. Amounts to maybe 4 or 5 degrees across the board, a difference that might show up on a dyno, but does not register on the old seat of the pants meter.  I was fortunate at the time to be working at a local college that had an auto tech ciriculum, and has an old SUN distributor machine in its lab.  I took all four in ran them on the machine and selected the one whose actual performance best matched its published specifications.  It happened to be one I pulled from a 54 Dodge Pickup in a junk yard. So now it sits in my 56 engine.  The one from the 56 engine was the runner up and it resides in my traveling kit, all set up and ready for a quick swap, should ignition difficulties ever rear their heads on a road trip. I have both numbers recorded in my note book in the box with the spare.  It contains info on other replaceable parts and crossovers that might come in handy should a breakdown require parts.  Belt number hose diameters, shock part numbers, and other relevant numbers for gaskets, seals and such.

[medium_jon]

Thanks for the question @greg g

My engine number is P20 316710

My youngest children's high school has an automotive tech program. I might have them take a look at this if I ever pull it. I had just been doing research on what I had and had taken those photos a couple weeks ago because I could see the label nicely while I was working on the breaks. When I tried to find it in the manuals and that is how I found it didn't match. 

Bad photo of engine number...

[dpollo]

The Plymouth and possibly all Chrysler products changed to the IAT from the IGS in about mid 1950.

The IGS is easily recognized by the counterweighted rotor.    My personal preference is the IAT  but in fairness, the IGS is  built better with a  ball bearing points plate.