If you're unable to find it, you can call customer service for Volvo Trucks. If you give them the VIN number of your truck, they can look up all specifications and details. Not knowing which country you're in, I'm unable to give you the number specific to your country, and the North American number probably won't be of much use to you, as cabover Volvos haven't been marketed here since the early 90s.
FH is a larger cab, and, IIRC, can be had with the D16 engine.
In countries where the FM is marketed, synchronised transmissions are the norm. The synchroniser gear means you don't have to catch the right RPMs to go into gear, but it also limits your shift range somewhat.
usually white smoke is caused by coolant getting into ignition chamber can be caused by a leaking head gasket, a cracked head or compressor needs rebuilding