I've been going through Baker pictures this weekend, and thought of this thread. I noticed that on the couple of A-Grades with serial numbers in the 3xxx range I have pictures of the dogs on the lockplate have their heads above the center pin --
3190 05.jpg
3190 06a.jpg
3545 04a.jpg
While on a couple of A-Grades with serial numbers in the 4xxx range the dogs are ducking under that pin --
4358 04a.jpg
4358 05.jpg
4981 03.jpg