Drove it around some.
(Sorry to disappoint you, Chris, but I won't be doing any purposeful burnouts anytime soon.)

.
So, driving it around today I notice a vibration that fades in and out. It's not a consistent
vibration at a given speed. It's the worst at about 38 mph. But it's not a consistent vibration at 38 mph, but rather; it resonates in and out while driving at 38 mph.
.
I'm currently reading up on the issue.
Threads I've considered so far:
http://67-72chevytrucks.com/vboard/s...d.php?t=694626
http://67-72chevytrucks.com/vboard/s...d.php?t=522180