Obscure question, but I'll bet someone here can answer it... )

Our old tumble-dryer is fading, and I'm pondering replacement options. One
key factor is that it vents from the bottom of the rear panel, approx
centrally. I don't want to buy a new one and then find it vents at top
left or whatever.

So does anyone (kitchen fitters maybe?) know of a source for dryer outlet
dimensions? Anything to avoid walking round Comet with a notepad, fending
off commission-hungry yellowshirts...

TIA!