Good luck on that
What I did I got Bimini hardware, the base,the tube end and a 7/8 or 1 inch tube and made my own out of stainless steel. To get a replacement arm is hard ,I could not find it long enough so I made my own and it works perfectly
The only thing to watch is when you screw the base in to the window frame be very carefull I used long screws and it cracked the window ( been replaced ) so use short screws and you will be fine
Make your own.