Changing out 5/8 inch lead screw

I have a Myford 7 with a 5/8 inch lead screw. Myford advises they no longer carry the 5/8 screw and only have the 3/4 inch. They think the lead screw can be eawsily changed out to 3/4 inch but they suggested I post on a forum to see if anyone has experience changing out the 5/8 inch to 3/4inch. Bill