Comment by Fokeman:
The most reliable site for Neat Records online is
https://thecorroseum.org/labels/neat.php which seems to be sure about the release date. So I suggest we go with 1987 until absolute proof to the contrary.
Comment by Fokeman:
I'm thinking that with the subtitle of Mayhem '87 that despite its recording date it was actually released in 1987. The confusing factor is the 1986 publishing date. But that doesn't necessarily equate with a 1986 release. Does anyone have any cast-iron proof that it was actually released and promoted in 1986 before several of the subsequent NEAT numbers?