Timing cover pitting.

Passenger side timing marks. Seems rare.
1969 only
Actually, now I'm confused. Some searching is telling me I should have the metal shim and bolted on passenger side for timing marks.

Mines actually casted into the aluminum on the passenger side, driver pump inlet.

Cover must be removed to replace crank seal.

I don't see covers like mine, they're all driver side indexed. I wasn't looking forward to spending money on a balancer tailored for a different cover
just remark your balancer to coincide with the new cover marks, pretty easy.

or buy a new balancer for $100 (yours is probably pooched anyway)