Replace window

In planning the bathroom renovation of my rental, I have ordered and got delivery of a vinyl replacement window. Please see my previous post on "fixture height". After tearing the wall down and the old window, the frame of the window was almost gone. If you dealt with these old, old wondows with a long cast iron ingot counterweight and a pulley you'll know what I mean. Quite often the vertical part of the window frame gets destroyed during removal of the old window because of openings cut for the pulleys and access door for the counterweight.
I think at this point I might as well return the replacement window. Pay the 15% restocking fee and get a new window. Tomorrow (Christmas day) Home Depot will be closed. SO I measured the rough opening and grabbed an Anderson double hung before HD closes at 6 today.
I have never installed a new window before. What do I need to know? What concerns me is the finish on the outside. The existing aluminum flashing on the outside may not fit properly. I may have to go to the local hardware store to have the aluminum sheet metal custom made. Advice is appreciated.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<< Advice is appreciated. >>
Relax and put it off until Tuesday. Meanwhile, get your window installation instructions out and read them. If you don't have any, call Andersen and get them. Pay attention to exactly what is called for in the install, like RO precisely 1/2" larger than the window frame, and all parts of it square plumb and level. Gather your supplies, like roofing nails, a roll of flashing, and especially shims, and latex foam ( not the hard expanding foam) for filling the gaps. A triple layer of heavy PE film over the opening will keep out the weather while you're getting organized. Good luck.
Joe
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Post a photo . who can see 100,000 feet away.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Andersen windows come with complete instructions and they have them on line and the size charts at their site. Do not start this project when the stores are closed.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.