Just from reading your account, I seriously doubt that this forged steel crank went for a 'walk'!
I also agree with what Chris mentioned - the crank pully/harmonic balancer is infamous for seperating into two pieces. This happens quite frequently in high mileage SVXs.
I have yet to hear of crankwalk in an EG33 (including the heavily modded ones used in dune buggy's). This isn't a 2nd gen dsm....
-Chike