I've got a project old truck I want to put power windows into.
The side glass is dead flat, like a G55. I have spare compatible one-touch Euro window motors and have seen the aftermarket G-Wagen front window regs that use an OEM motor. They're a whole lot cheaper than the "universal" power window kits from Electric Life. Gut feeling is, providing the truck glass is not taller than the G glass, it can work.
But I don't know anyone with a suitable Benz. Hence the request; if someone you know has one, any chance of a post or PM with the glass height from waistline rubber seal to where it disappears into the door frame at the top? It would be a bit weak to join (say) the Peach forums to ask one question.
Where's your nearest merc dealer? Just walk in with a tape measure!
A friend would relish that challenge! He'd probably try to get a test drive out of them, too.