I tried one of the Alloy Metal harness's for my 69 BOSS. Advertised as and exact reproduction. I ended up sending it back. The quality was nice enough, but 'EXACT details', no way. Some connectors in no way duplicated physical attributes of the original connectors (e.g. headlight connectors were much lighter duty on the reproduction loom), though functionally interchangeable. Other connectors looked like perfect clones. Where there was a branch in the loom, the original loom has a special molded plastic fitting to emphasize the branch, the reproduction loom had nothing, other than the tape wrapping to make the branch demarcation. A functional replacement loom, yes it is, an exact reproduction, no way.
The after market manufacturers will make and get away with what ever the buyer is willing to accept or not want to know. Not enough complaints filled IMHO.