OC500LEs are now very common for service 171 already. Not so
common ones are services like 854. Whereas service 853 do not
have any OC500LEs nowdays but rather Nissan UDs instead 
.
Other not so common OC500LEs in CCK includes service 67 and
188. In Bt Batok you can also catch OC500LEs on feeder service
945 as well.
For Woodlands you got to depend on luck on services like 169,
925, 926, 961, 965 and 969... 
925/926 Is more luckly! Last time only saw SMB31X on 969
