Your firk is a P-Bone, not a Fatty (straight legs instead conic legs). Should be 97 or more.
you just have to look serial number and to go to vintagecannondale.com
Re:
My first HeiHei serial number was 16007. But the rear dropouts got bullets like 1993 and really early 1992 HeiHei got different dropouts with Mc Mahon/ Sandvik design
Very heavy (only steel made) and gears are limited for climbing. Brakes are non-existent. Cantilever suspension is very soft and works in every pedal stroke. But, it's so cool !!!!!
The 1982 Motobecane catalog show that strange bicycle with rear suspension, indexed Positronic Shimano gears…
MTB as we know today landed in 1983 in France. So, the Velover is not a Mountain Bike but it was ready for riding on some off road tracks.
First time we could see a mtb extralight : 1993 Mountain Bike Action… but it was only a prototyp
(https://www.retrobike.co.uk/gallery2/v/Manufacturer+Archive/Merlin/Reviews/Mountain/mer4C.jpg.html)