Thriller featured criminals escaping on bus, painted over roof numbers

I distinctly remember watching a crime thriller film in the 80s, probably a Made for TV movie, where the criminals used a bus for their getaway. I recall it was an ordinary bus and they painted it grey or maybe a prison bus they painted to look like a Greyhound bus. There were numbers on the roof and I think that they became exposed when the paint washed off and that gave them away. Sorry I can't recall much more than this, but I distinctly remember that a central part of the plot was painting the bus to get away. Any ideas anyone? A Google search has been hopeless. I just get stories about murderers on buses...

Interesting as that reminds me of The Train (1964) where the top of the train is painted white to fool aircraft.

The Train is one of the all time great war films.

This film was either late 70s or early 80s and I am pretty sure would have been a TV Movie. I was set in the US and was in colour and was probably in LA. I don't recall there being any stars, I just recall criminals using a bus as a getaway vehicle and they painted it because of the numbers on the roof.

Were the criminals the only ones on the bus?

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That sounds familiar, but could the vehicle have been a delivery truck and not a bus?