Boss head countersunk 3/8 x 20 B.S.F.

[Michael R.]

Does anyone have a source for 5/16" and 3/8" slotted countersunk boss head (or round head) bolts as used on the Carriers?

Alternately, does anyone have the ability to get a dies made for the 3/8" - 20 B.S.F. that will run in a standard Hartford header and screw machine.
The die making, set-up time for the two processes makes this a pricey option, but economic if there is volume.
Early days yet, but it may be possible to make a similar profile with a modern thread, which would also make it easier to find nuts.


A PM or e-mail if you have an interest in buying any if I am able to have them made.


Bolt - 5/16" B.S.F. x .87" boss head
Bolt - 5/16" B.S.F. x 1-1/8" countersunk round head
Bolt - 5/16" B.S.F. x 1-1/4" countersunk boss head bolt
Bolt - 3/8" B.S.F. x 7/8" boss head
Bolt - 3/8" B.S.F. x 1" countersunk round head
Bolt - 3/8" B.S.F. x 1 1/8" countersunk round head
Bolt - 3/8" B.S.F. x 1-1/4" long countersunk round head
Bolt - 3/8" B.S.F. x 1-3/8" countersunk round head
Bolt - 3/8" B.S.F. x 1-1/2" boss head countersunk head
Bolt - 3/8" B.S.F. x 1-3/4" countersunk round head
Bolt - 1/2" x 1-1/2" countersunk round head 8 used on towing attachment