Make sure all body parts are grounded to the frame;
hood, doors, engine block (should already have a
braided ground strap), body (bond sections together),
and especially the exhaust pipe. The exhaust can act
as an antenna if it's not grounded to the frame.
Disassemble and clean and reassemble all ground
There are shielded spark plug wires to try. Maybe run
shielded power wires to the rig. There are probably RF
chokes still available for the power wires. They used
to sell them for fm radios with noise problems.
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