Although the original five aircraft from Flight Unlimited II 
don't have any autopilot controls displayed on their instrument 
panels, you can still have full autopilot functionality with 
them by using the appropriate hot key combinations. 
Press A to toggle autopilot on or off; Alt-A for altitude 
hold; Alt-H for heading hold; Alt-N for NAV 1 hold; Alt-S 
for speed hold; Alt-V for vertical speed hold; Alt-W to 
level wings; and Alt-M for instrument approach hold.