Wiring harnesses

American Autowire is NOT M&H. American Autowire makes kits that have to be assembled, M&H sells direct replacement original harnesses.
Year One numbers are:
Engine forward harness: 1973 V-8-HU2, 1974 built before 10/12/73 - HU10, built after 10/12/73 - HU11
Dash Harness: 1973 - HU326A, 1974 - HU327A
Rear Harness: 1973 - RL73, 1974 - RL78
There are some model specific sub-harnesses for stuff like AC that are also available

These are very specific, very accurate reproductions.