You've just GOT to install those big 7" amber LED turn signal lamps on the back of your 4905! The red brake lights, too!
Their visability is awsome, compared to the OEM bulbs.
All the local school districts around me have changed their Crowns, Gilligs, Blue Birds & Thomas's to these, and we've got a good supplier here in town - California Bus Sales. If you ask real nicely, I might just mosey on over there and find out how much damage they'd do to your pocketbook.
CBS carries the better LED units, the ones that have a gazillion in them. They've got a lot of other LEDs, too, for side turn signals, clearance lights, interior lighting, etc. They also carry the bases, those elusive critters that you mount the lights to.
If interested, send me a note - you know the email addy. . .