Joe45
Regarding galvanic corrosion -- you only need to use a layer of tape (packing tape would work) between the Al and steel frame.
I will most aluminum frame windows are pretty cheap though...
The Al will conduct heat/cold to the outside pretty easily.
I was always amazed that the windows in my 1962 Fireball camper were better than most of the windows used in houses built in the 70's to '90 in Fort Collins, CO. Super cheap aluminum track windows -- I use them for a green house but not much more...
But I also respect a no-money budget hence the suggestion for scotch tape which is exactly what we used to install the steel bearing housings on the aluminum pillow blocks of the tail rotor drive shaft on a Huey (UH-1H) too easy!
I used butyl tape and foam rubber gaskets.

