Thanks to everyone who has responded, some with photo's, regarding my question as to which type of 3ttt Grand Prix bars I need for a 1968 bike.
It appears that there are at least 4 styles of logo's associated with 3ttt bars [pre concealed cable ones]
I now believe the earliest logo is simply stamped ttt with Grand Prix underneath, this is on the right hand side.
Maybe the 2nd logo would be a 3 with ttt inside a box on both sides.
3rd logo with the olympic rings.
4th logo with 'laurel leaf & sheild' logo, which may also say 'mod Competizione' or Gimondi, TDF I haven't botherd to mention the later bars suitable for aero brake cables.
Of course there is also Ambrosio to consider.....as I believe Ambrosio eventually became 3ttt.
Thanks once again.
cheers.........Kevin Sayles Bridgwater Somerset UK