Broach marks are the marks left on the block surface after it is machined. Back in the 60's it was done with a machine that left straight lines going from front to back. Machine shops usually surface a block and leave circular marks instead. Here is a pic to see the orig type marks, Hope I explained it. People faking cars quite often surface the block and then restamp it to make it #'s matching so it is important to examine the broach marks to make sure you are not getting a fake.
