Timing cover pitting.

junkyardhero said
1969 only

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)

If it comes loose I'll just try and center it and weld it together. Did that on a Chevy tracker 4 banger. I used welding rod stubs for equal shims all around center.

Redline it often @ 6500.