I recently bought a '64 C10 with a 6cyl. The engine has F0607CS stamped on the pad behind the distributor which from what I can find online looks like it's a 250 from a '67 chevelle. The problem I'm having is that the balancer spins about 1/16-1/8 turn freely on the crankshaft and wobbles quite a bit while running. Here's a picture of the balancer on the truck.
It's been several years since I've had a 6cyl but on all the v8's I've had there's always been a bolt with a large washer that holds the balancer on and I assume the 6cyl should be similar but there isn't a bolt on mine. So my questions are, should there be a bolt? I tried sticking a small screwdriver in the end of the crank and it only went about half an inch into it. Does that mean the bolt likely broke off? I'm having a hard time finding a replacement balancer at the local auto parts stores, does anyone have a part # for one that will fit? Thanks for the help.