Right. here are the bushes in the linkage.
Gearbox nose cone brass bush (not shown in StuF's diagram). removable with gearbox in (remove nose cone) from memory. remove drive shaft, unbolt child assembly.
Gearbox input shaft (31)-longitudinal linkage rod connector (fork connector) Keep the gearbox in. unbolt coupling, pull gear lever back to seperate.
"Shuttlecock" bushes (13, 16, possibly another 16)- You cannot replace the rear 2 (or 1, depending on the age of the bus) without removing the gearbox. You CAN replace the front one- disconnect the linkage rod as if you were changing the fork connector, disconnect the front linkage rod, push the big 'un through until you see the front bush.
Front rod bush (19)- on an early, that's a wee slip of the thing. Easy to change, take the gearstick out, undo the front coupling between the front rod and the main rod, take it out and change the little bush inside.
And that's all of 'em

Once you've done that, do yourself a favour and fit one of those £5 quick-shift kits. Cheap as chips and make a real difference to the feel, plus they keep everything looking stock.