@Bow_Tie,
I noticed something when I had to replace my window regulator Drivers side, here recently and that was the regulator pin, the thing you put your window crank on, is longer in some years trucks. The regulator I got from a wrecking yard was off a '77 Surburban. Unless you get the correct window regulator for the year panel you are replacing, the pin will be either to long or to short. The pin from the Surburban was a little to long, but okay so long as it was smooth operating that's all I cared about.
I wanted to get a '73 window regulator recently, because it was $19.00 with some guy on Ebay, passenger side, and the seller said his book said the '73 regulator would not work in a '74. I knew the panel was just like the panel in my '74 but there must have been some kind of difference where it wouldn't work. So I bought a regulator for a '74-'76 C10 from some car parts site for $39.00. And when I got it the pin was the correct length for my door panel.