Plymouthy Adams

you need to get up to speed with the ignition system and what creates the spark and trouble shoot from there....if you get a strong spark with the screwdriver arcing the points, your coil is working.....sounds like you points are not opening at all (this is when the spark is created on collapse of the field inside the coil) OR you have shorted the two contacts at the wiring connector at the points.  By your note you saying you are holding the high tension at the distributor to ground....it must not be ground but a gap so you can see the secondary voltage spark as it jumps the gap.   Again, check for short in distributor.

😴

The actual capacity is stated in the repair manual on the lubrication chart.  It is not specified in the box with the picture of the differential and interval for checking/changing but rater in the legends at bottom right corner under capacities...the amount is 3 1/2 pints.  

if you plan to seal it....seam sealer and RTV are not your friends here IF for some reason you should have need to remove the strip down the road.   A good dum-dum putty found at the local paint and body is a very good product that is easy to apply, remove, work with as needed.  

also you should pay close attention to the isolation mounts, front of engine, at the transmission cross member and do not overlook the fact the rear shackle bushing could be shot keeping your driveline out of phase or grounding......and couple this with higher than normal idle speed....you can creep....good inspection is needed, tune per specs/verified a must.

trim line...some better insulation I have been led to believe....cannot confirm or deny....most it is additional body trim, higher grade trim, some interior upgrades and other options are now stock on the higher line.  You bought the custom over the deluxe to keep from filing out and ordering a deluxe with this or that and wait for it to arrive.  

1954 the PS did not state the need for the larger engine, this come about in April with the introduction of Plymouth first fully automatic transmission...the only year Plymouth offered two different displacement flathead 6's and the larger 230 is identified by a diamond ahead of the engine class/number

odds are this was installed to level the car due to one spring being weak or of a different tension when possibly repairing a collision incident in the past.  The spring are marked with matching numbers and you can verify if this is or is not a matched pair.  If you retain the spring, and, it sat level and drove well, let a sleeping dog lie.  

there is a removable expansion plug over the bulb in the head....allows you to access from there.....you will need a good solvent to break the rust bond.  This is delicate to remove intact....go slow.....and yes it is one piece with the gauge as you state....damage renders it useless unless you perform an effective transplant from a modern donor or luck upon a surviving unit or NOS

there is but one frame shown for the P15 in the repair manual, the center mounts bolt to the frame...they are positioned per body being used....these again, bolt where needed and the holes are provided by the factory. These movable mounts are in the vicinity of the B-Post.....as I have a bz cpe here I can assure you that it matched the frame dimensions in the book.

this came up with a three key word search...are you searching the forum and using the proper syntax to get the pertinent information?   I found this quickly and refers to what you are asking for.....go from there
 
 

if you plan on running radials throw these caster measurements in the trash can...

4 3/4 -6

Dodge and Plymouth are two different size bodies and frames for these years....not a bolt on....got fabrication skill...go for it as it is already a custom build...else, modify the Dodge doors as the work will be easier with the already fitting door on the Dodge to modify the fender sweep that extends into the door.....OR...find yourself a 41 Dodge and check it as the bulge was not existing at this time. 

per my experience you are upside down...with the help of another set of hands, the inner fender liner removed....a lever, s hooks, chain and Bob's your uncle.

yes, ethanol has made a lot of issue come to the forefront on our old beasts.  Some suppliers address this and supply parts for the upgrade.  But there is hardly a week go by here that some poor soul has not started a thread to the failing mechanical fuel pumps.  Personally I have never had one of these failed units in hand by the obvious statement above, the electric pump is my full bowl of soup.  If out and about, an electric pump is near to hand at most parts stores and the ride home on the flat top less of a worry in the back of your mind.  If running 6 volt, a spare electric is very affordable and cheap insurance in the 'kit' many I hope do have in their trunks.  Many of the older style pumps say AC, Purolator, Carter etc physical size and often crude mounting makes them a bulk item even given you could find kits.  How many vehices made today would have a mechanical pump...things change for a reason.

what did Bernbaum have to say about this besides, sorry send it back or shazam we sent the wrong part.    My speedline can only supply the mopar number,  670 752  (neopreme without felt)
 
this is the cross I found
Performance Part   Superseded Part Number 1671763 Country/Region of Manufacture United States   OE/OEM Part Number 670752, 1486096, 1550929   Interchange Part Number Victor 49318, Victor 49075, Trostel A85037S, Trostel A48074S, Chicago Rawhide 15620, National 471827    

don't guess...do a voltage drop test and know for sure where your issues lie....do consider looking again to ensure your timing may not be too high...do a current test to see if you starter is dragging due to worn rear bushing....you have a host of simple easy test with the most basic of tools, use them.  

This is fairly common for this era...the holes for the tumblers are frayed over into the key way.....you can grip with a vice grip and tap on it....BUT you are going to need the key in to remove the cylinder for you are either going to dress the hole for a possible short term fix or best to replace the cylinder.  If you wish, with the new lock you can key it the same as the original key and cylinder.  You will need to tunr the key when you remove the steering wheel and access the cylinder retaining pin.  

the D19 is typically a bit larger body than the lil sister Plymouth not to mention the curve of the butterfly could be distinctly different.  

this under color is normal, it is called ecosheen and can be greenish to a grayish color depending on year and place of assembly.....

.030 of stock or max dia. 11.060  Most all shops have this and will not turn beyond limit...even if on a golf cart.....

clockwise to retard and about 4 degrees if using lower grade fuel experiencing pinging on grades

you in luck, have this one in the shop lying about for easy photographing.
 
 

per the description of the cluster and bulb arrangements and per the schematic you have listed and followed, there is but one single wire going to that bulb...it comes direct from the P terminal of the flasher....perhaps you have a bad flasher.  It is not uncommon to get a bad 3 prong flasher as most are not made well today.