If you are that bored, pull the engine or gearbox out and fit a new seal. You might have to buy a modified seal housing or get a late model housing to upgrade it from felt to neoprene.

Make sure you are using the right dielel oil too, you want a "mixed fleet" type, that caters too older European & Japanese trucks wuth flat tappets. American truck Diesels are roller follower at the cam, i.e., the old GM has been roller lifter since 1938, Cummins since the 1950's, Caterpillar about 30 years ago.

The Buzz could be an exhaust rattle, the dual pipes are tuned in the 3000-3500 rpm range. Look for loose tinware attached to the motor, not in the motor. Save the money & effort for something else. NEVER BREAK THE MECHANICS NUMBER ONE RULE.

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69 142S Overdrive + 69 164S Manual