Bolt - 7/16 inch UNF x 3 inch
Spanner size 5/8 AF
Hexagon Headed
20tpi
Note: A factory modification on TR6 in 1971 deleted the use of locking
washers on main bearing cap bolts, shorter bolts being introduced at this time.
Bolts measuring 3" from under the head to the end should be used with
locking washers, whereas the less desirable shorter bolts should not.