Thanks to a 37 year-old brochure, I have an answer to the power windows/power vent windows question. I have a 68 brochure (the one my parents got when they bought a new SDV that year)and in the Calais section it says, "Both Calais models for 1968 NOW (my emphasis) include, as standard equipment, power windows",so as late as 67 you could buy a Cadillac with manual windows. In the Fleetwood Eldorado section, it says "the power control panel on each door, above, controls both the side and rear quarter windows" (just a regular four-window control on the vertical panel). In the optional equipment section, no. 7 says "power vent windows can be operated from a convenient control panel. Front and rear, standard on the Fleetwood Sixty Special and Brougham, rear quarter on Eldorado and front on Seventy-Five sedan". Since they were standard in 68 and the ad shows pictures of manual rear cranks in 67, apparently 68 was the first year they were standard. I was also surprised to discover that the seat bolsters in cloth-upholstered FLEETWOOD Eldorados were vinyl, not leather. Someone commented on front-only power windows. They were pretty common in the early 50s (I have an ad for the 51 Chrysler Imperial convertible and it clearly shows power window controls on the drivers door and a crank in the rear). This was really inconvenient in convertibles and very strangely is still the way Chrysler/Dodge Neons come.The downsized GM intermediates introduced for 78 had no way at all to lower the rear windows on sedans and this continued for several more years. The middle of the door had an upholstered inset where the window mechanism would have been. GM touted this as increasing rear-seat shoulder room, but it was clearly just a way for them to save money. The rear-quarter vent panes were able to be opened, either manually or electrically on power-window cars. My aunt and uncle bought a loaded 80 Cutlass Brougham sedan and when they got home with it, they called their salesman to find out how to lower the rear windows and were told they couldnt.