There’s only so much room for the description in the pars book Lonnie. I mean they could further tell
you how much thread there is and whether they are plated and the head size but they don‘t. Those bolts
are not meant to be tightened up tight, instead they are used for the adjustment of the mount. There for
they have to have a way of locking them after the adjustment.
I don't ask this often without having documentation but, trust me, the original “special” part number
bolts were drilled for a cotter pin and were threaded only far enough to put a little tension on the rubber
pad. I have the original factory outer bolts in my mount but like you I choose not to use a cotter pin and
like you, I choose a Nylock nut. Any other self locking safety nut could be used, but originally the slotted
nuts were pinned.
There were no ½” bolts used in the front center motor mount for the 6cylinder Chevy trucks,
unless someone got the drill out and opened up the holes.
Don’t know where you got the “Hardened carriage bolt” from Lonnie, that is not a hardened bolt just a
specially made carriage bolt. My guess for the two numbers on the nuts would be that the were supplied
with different style castle (same thing as slotted) nuts at different assembly plants. West coast plants
where fastener suppliers catered to the aircraft industry may have even supplied self locking nuts.
Denny Graham
Sandwich, IL
Last edited by Denny Graham; 02/11/2012 6:35 PM.
