Quoted from kvolak:

In progress going through my Taxi , but I'll post this here so it can help other noobs like myself:
Topper: #555 x 4 and #906 x 4
Backbox: #555 x 8 (for the traffic light and Williams Pinball Palace sign), #89 x 7, and #44/#47 x 33
Topside/GI: #67 x 2 (under Departure/Arrival ramps, #555 x 9 (for the Spinouts and Pop Bumpers), and everything else topside is a #44/47 (still counting exactly how many)
Inserts: #906, #555, and #44/#47 (still working on the inventory)
I plan on making a cheat sheet that says which size bulb goes where, since the bulb matrix and schematics look like Greek to me. I know Taxi is the first game for plenty of people, who may be trying baby steps (like replacing bulbs and rubber rings) to repair and maintenance.