Did you put the diesel sock? The diesel sock should be good but sometimes people replace it with gasser sock which is problematic.
A new Fuel Pick up kit comes only with gasser sock which needs to be replaced.
As for the LP, which Carter pump model did you buy?
Carter is just a brand.
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There is a shaft, the seal is around the shaft.
It may still be outside the cover.
When I replaced the HB/Crank Pulley, I gave the mechanic a "round seal with lips" in addition to the pulleys.
Will said, it is called "front Crankshaft seal"
It has been a while but somebody should have a...
Not solving the scanner communication issue but since you are worried about transmission.
How is the Transmission fluid condition?
Sometimes, transmission problem arises from neglected fluid or even low level.
When I did mine, I just find a Youtube video on it.
It is the same for gasser or diesel.
Follow their direction.
Not sure if yours has been modified then you need to post picture on what is the current situation.
JMHO.
There is no such thing as the most reliable battery.
You can buy battery from the same mfg or brand, sometimes it is good for a long time, sometimes it is short lived.
The objective here is to buy it from a place where you have access to replace under warranty wherever you are.
Did you connect the extension cable correctly?
There are orientation on those cable but it is not clear on the extension connector.
Where did you buy the cable and PMD from?
The tricky one is the extension cable and some Dorman PMD have been known to be DOA or now working properly even when new.