1974 NASCAR International Stock Car Racing Rule Book Grand American Cars Section 20A-5 -- Frames

a. Frames may be reinforced, but must remain unaltered in every other respect. Wheelbase must remain the same (plus or minus 1/2" overall) as manufactured in reference to measurement from the front door jam post to the rear axle. Maximum wheelbase is 112" -- minimum 100".

NOTE: For AeroWarriors.com users, Grand American Cars are governed by the same rules as the NASCAR Grand National Championship Division, with the exception of this Section, and the following:
Section 20A-1 -- Competing Models
Section 20A-2 -- Engine
Section 20A-3 -- Engine Mounts
Section 20A-4 -- Minimum Weight
Section 20A-6 -- Ground Clearance
Section 20A-7 -- Wheels