IIRC Mymopar doesn't have the '74 Shop manuals but they may have the extracts of the wiring diagrams included in the Wiring diagram zip file. I say that because I have a digital copy on my computer/
View attachment 1716473503
Yes the wiper connector also has the backup lights and key to starter relay wire.
When reading the factory diagrams.
R is for alteRnator wires
A is code for bAttery wire
J is code for Ignition (interpret that loosely). J2 is Ignition Run and engine related including alternator feed. J3 is Ignition Start.
L is for lights
H is for Horn
B is Backup
S is Starter
V is Wipers
S is for Start and since yours is a '74, the seatbelt interlock made the start circuits more complicated.
There's a 1974 Master Tech filmstrip and booklet about using the new style of diagrams and explains all of the wire codes.
pdf version here:
Browse MTSC by Model Year – 1974 – MyMopar
Use the wiring diagram to make your own drawing of the circuit(s) you are interested in.
Complete descriptive listing of the Master Booklets and films is here:
Master Technician Service Conference - Chrysler's Training for Mechanics
Once you know the year to look under you may want to go to back to the mymopar website to view them in pdf format.