if you ever have to replace door glass of a 78 wagon from a 74 wagon. take all of the internal parts due to fords changing the mounting points on the bottom of the glass. case in point.. last summer some kid with a pellet gun shot out my passenger side door glass on my 78 wagon. i had to use the usuall plastic bags to cover it up till i found new glass for it.this week ,a 74 pinto wagon came into my local pick and pull. a buddy of mine wanted me to look at the motor cause he was not up to snuff on his 2.3's and sure enough, had good door glass. so i was suprised when i opened it up. and saw how much difference there was in the mounting points and after you get all of the parts together. converting late model doors into 74 and earlier is very easy.74 window regulator are all stamped steel and has 3 arm mounting points and tracks. the 78 is part steel/ alum. and has one mounting arm point and a slider assembly 3/4 of the way inside the door that supports the window. all the mounting holes are the same. the 74 had bolts mounting the assembly to the door. the 78 was half bolts and half rivets.which you will have to pop and drill out and replace with either rivets or 10 mill bolts
hope this helps someone