Topic: 65 Bolt Confirmation on Rear of Door (Window Track)

[1965 t5]

I am looking for confirmation of the 2 bolts that were used to mount the rear window track to the door (visible from door jamb).  I have 4 doors at home for a 65 that all have signs of the serrated bolts (all of which have SEMS head marking).  All the other bolts for the hinges and all window hardware are not SEMS and they have the larger toothed style washer.  When I look online, SEMS bolts are listed to start later.  Can anyone offer help on this?

[ChrisV289]

When and where was the car built? Might determine the head marking.

[1965 t5]

Jan of 1965 in Dearborn.  thanks

[jwc66k]

I am looking for confirmation of the 2 bolts that were used to mount the rear window track to the door (visible from door jamb).  I have 4 doors at home for a 65 that all have signs of the serrated bolts (all of which have SEMS head marking).  All the other bolts for the hinges and all window hardware are not SEMS and they have the larger toothed style washer.  When I look online, SEMS bolts are listed to start later.  Can anyone offer help on this?

There was a transition from the external tooth lock washer to the disc with the serrations on the disc's edge that occurred in 1964 thru 1967. This was a Ford decision, Mustang just happened to be in production at that time. The screws you are referring to are 3/4 inch long (378735-S2) and those "may" have been the first to be affected. In many cases of changes in design, Ford required old stock to be used first and said to use old and new interchangeably. There are instances where both type of lock washers screws were used on the same car on the same fender. The best guideline is see what lock washer imprint is on the parts and go with that. That is about as ambiguous an answer as can be found.
Jim