What is interesting is the entry point for the fire selector is the new Russian oval style instead of the older style that is seen on the 84 style and Bulgarian style AKS-74Us. It seems like most of the "correct" receivers for the 1986 AKS-74U is incorrect due to having the "Bulgarian" style entry point, including the 74ULLC receivers.
Newer Russian style
Older Russian/Bulgarian style
1986 AKS-74U with the newer Russian style
1984 AKS-74U with older Russian/Bulgarian style