When I owned a 4-108, the engine was fitted with a separate oil pressure sender screwed into the oil gallery directly on the port side of the block, and the low oil pressure alarm switch was screwed into the remote
filter housing right below the injection pump
. Worked fine....
That said, there is no reason that you couldnít use a proper ďTĒ fitting with both sender and switch fitted into it, or a multi port manifold connected to the oil gallery with a small hose. Both have been done successfully.
shows both options.....a heavy duty ďTĒ fitting made of steel
that isnít going to crack, and also an aluminum
manifold to accept all sort of senders and switches. The small threaded holes in the manifold go all the way thru and are for mounting on vibration isolators.