M code barracuda

Well since that wasn't a body in white, special order race car if you imagine the warranty issues if they would have stuck a 4-speed in those bad boys? Brutal! Now I've talked to a couple people that actually own original numbers matching ones, what I can't figure out is where the 383s and 440 cars, (H and M) built to Magnum specs Factory?
Yes, in 1969 the 383 A-Body's had 335 HP engines but were rated at 330 HP because of the restrictive drivers side manifold. The 440 was still rated at 375 HP in an A-Body...