Just thought I would post my Centurion Mountain Bike if that is any use.
It is a Centurion MT 1800. Not sure of date, but would be earlie 80s due to old cantis on it. The shifters are early 6spd thumbies if if remember right.
The serial number is F8014218 and it is made with Tange Double Butted Mountain Tubing.
utedeej