If you read what I posted: have you followed those instructions and polarized your generator every-time/any-time you disconnect/remove/replace the generator and voltage regulator.

Why not just do it now - it cannot hurt, and, it might solve your problem?
http://fergusontractors.org/nfs/wp-content/uploads/technical-articles/Polarizing-a-Generator.pdf (about tractors, but pertains to our trucks with generators/volatge-regulators).

Here are noise suppressor/suppression instructions for 47-55st Chevrolet trucks.

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.