Except for the Hungarian "Ikarus" 260 buses and Hungrian-Serbian "Ikarus" Zemun ("Ikarbus") IK4 and some '70's Romanian buses and trolleybuse which had "M.A.N." 750 body stile (the buses where made under "M.A.N." licence), all the buses and trolleybuses that runed in Bucharest since I was a child had a syde display too - some indicating only the number of the line, other more infos (the 2 ends of line - at digital display, the 2 ends of line + an intermediary pass and analogical display - only "Saurer" 5DUK-A buses converted into trolleybuses had such display and it was a rolling one). But it was intresting that some drivers, at Romanian <<Dac>> x12E and x17E trolleybuses put also the ends of the line and an intermediary point on the side card.
And intresting form of dispay was this:
http://ratb.stfp.net/Data/A/s/304-781-Dn:1.jpg (nice "S.A.V.I.E.M." SC10U buses bought from Paris)
All the Romanian (except for the 2 axeled ones, which runed on rute 44 up until aorund 1985) and Czech trams (streetcars) had side display too. The ones bought second-hand (s.h.) in Bucharest from Germnay didn't - except for the "Rathgeber" P 3.17 + p 3.16 (so called "Rathgeber" "gras" - "fat" "Rathegber").
http://ratb.stfp.net/?ttx=Tr&veh=2008&all=Y
http://ratt.stfp.net/?ttx=Tr
Hope I dind't poluted your topic with Romanian stuff 
I
f any one is intrested, I can open a topic about public transportion in Romania.
Hope one day one of your old "G.M." buses will parade to the streets of Buchaerst! 