The measurements in the P&A are taken from the seal surface facing the stick end. The problem is that the stick shown is generic in that it has a washer and a seal and no bell.
Stop the press. Just found something interesting in my 67 Corvette AIM that may explain the purple button.
'67 Corvette big-blocks had dipsticks with pink (salmon) buttons, both before and after the mid-season running change.
Thanks for the information about the Corvette mid-season (3-3-67) dipstick change from 3860316 to 3925520, both with pink (salmon) buttons.
Now, if you look at the 67 AIM L35 A4 everything starts to fall in place.
The first production BB's started in January ? 67 and had 3902339 dipsticks with purple buttons.
The revision record shows a change in 2-8-67 from the old dipstick 3902339 with purple button to 3860316 with pink (salmon) button and then another change in 3-3-67 from 3860316 to 3925520 with pink (salmon) button. This coincides with the Corvette mid-season (3-3-67) change stated above.
The index of part numbers at the top of AIM L35 A4 never reflected the change in the color code identification as it should be pink or salmon and not purple.
This does lead to the question as to why was the dipstick changed so many times when the tube 3899640 and pan 3958658 where never changed until 68.
In 68 dipstick changed to 3925599 with yellow button, tube 3928901 and pan did not change. Same for 69.
Which engine went into production first the L78 or L 35? This is important as early engines should have dipsticks 3902339 with purple buttons
Pan # 3958658 is wrong and should be 3929257.