[pbowler]

My abiding memory of DMUs in the late 50s early 60s on spotting trips is the rattling windows but as Phil points out if you were in the front seats you could see the the smoke box door number plate of approaching locos, a big improvement on looking out of the carriage window specially if the steam loco in charge of your train had a self cleaning chimney, and even if it hadn't you usually got bits of ash in your eyes. A lot of the DMUs I traveled on had Gardener 150 engines, great for Scamell Highwayman tractor units that never had to go over 35mph but not much good for anything else. But above all else they were a good old reliable plodding diesel engine.