I am having the hadest time finding a rear passenger window regulator motor fo my 1978 Olds Delta 88. Can I only use 1977-79 Delta 88 & 98 Olds cars or can I use something else? What company can I find these at?

 

Rockauto seems to have them for both sides - about 70 bucks each.
A-1 CARDONE Part # 4217 is listed for the passenger side.
If you click on the part number in their catalog, you can see what else it fits to maybe find them in a junkyard.