It appears there are three VHS releases of Vertigo that began with the 1985 Hitchcock issues by Universal. These use the same art for Beta, VHS, and LD. All the VHS titles simply credit Dolby system with the Dolby logo and no hifi mentioned anywhere. The beta Silver mentioned may be the same as this VHS in audio. Then there is the purple Hitchcock Collection VHS which IIRC is from about 1995 or so.
I think this one is hi-fi. The third is the restored version which I have. Any one of these early copies could have the mono, and I'm betting it's the same source as what was used for the 5th generation DVD mono-but you never know..maybe we could pull more quality out and maybe there aren't so many dropouts.
Thanks for saying that AF. I always thought when looking at comparisons that the supposedly bad first DVD actually looked better in places and like the 35mm restored print. It was probably directly print sourced for the LD then ported, and the later versions from a HD scan retimed and tweaked for DVD. I think the correct is a compromise between the two. Who knows what the studio will put out. They seem to have neglected these films since 1985.