I removed the bracket on the left from a ('66 ?) Fairlane V8.
The bracket on the right was on a '63 170ci Six, but appears incorrect:
it has two mounting tabs, but the '63 170's block has but one mounting
hole.
Thor Johnson <johnsonta@hotmail.com> says that he had the bracket
on the left on his '64 170 used to have the one on the right, and that
his block also has two mounting holes, but that there was no way to correctly
orient the coil/bracket, so that the coil wouldn't point to the firewall.
He changed it out for a bracket from a '65 200.
The Pertronix FlameThrower measures 2-1/8".
It does not fit very well in the OEM mounting bracket. The bracket is adjustable, but the clamp screw hits the mounting bolt. Beware!
Coil on left is from Fairlane V8; coil on right is dead one from '63 170ci.