I tried to coax them out...no go.... so hammer, chisel and crowbar. Not pretty by fast compared to being kind.
Wynne Enterprises made me 16 windows for around $3500....the expensive ones were the hinged ones...the sliders weren't too bad.
They are in Tuscumbia, Alabama..... 256 383-5040.
They make large numbers of windows for RVS, school busses, etc...and some for boats. Not top of the line but nearly as good for less than half the price.