Bike Forums - Difference between Apollo MK V and VI?

I posted in another thread but thought I would try and gather further information as there is not all that much available. I notice a fair amount regarding the IV and some oe the VI but the MK V is somewhat obscure. Perhaps a one year only model? Asking as I am looking at purchasing a 56 cm frame that is in at least good condition. I was thinking of cleaning it and mounting the frame on a wall but more likely going to build it up.

Seller mentioned there is a slight shallow indentation along the seat tube from a clamp but cosmetic in nature. Doubt one could have it taken out. It can be somewhat noticed near the Fred Deely sticker.

Hopefully the differences as well as years of production and by who can be clarified. Pictures of other MK V and VI if possible would be great, I imagine T Mar might want the serial number for his data base.

https://cimg4.ibsrv.net/gimg/bikefor...d53da0e363.jpg
https://cimg9.ibsrv.net/gimg/bikefor...9b52c080ff.jpg