Round or Flat Bolt for IBM 3,849,xxx ?

[BrianQ]

Charlie, if I remember correctly the X is to show that certain revisions had been made to the design of the round bolt.

The X indicates the revisions were not made, only the elimination of the top cut.

[dbarn]

Thanks Brian, that certainly makes more sense.

[painter777]

Brian,
When you say ' only the elimination of the top cut'
Do you mean the extra milling that would have made it a Flat Bolt?
Sorry...... But I'm a little lost here.

TIA,
Charlie-painter777

[skohler]

3.89 m with original AOB round bolt, x on the top.

[Magnum Mikie]

Charlie, I have 3857121 and it has a round bolt marked AOB with an X on top.

Same here. My 3,910,xxx also has AOB round bolt with X.