Jamo is correct. It should be bolted to the inside of the aluminum firewall, passengers side. Be sure to use the rubber mounting studs that they provide, as they offer insulation and shock absorption qualities. Also, be very particular where you locate the mounting holes, as you need to make sure there is adequate room for the puke tank which resides on the opposite side of the firewall. You don't want to inadvertently have a MSD mounting stud interfere with the puke tanks mount.
Bud
