Any decent auto glass place can replace it for you. I would make arrangements to buy the seal at a dealer or independent shop or parts supply that can get a real OEM seal. Do not under any circumstances save money and buy an aftermarket. The OEM is a one piece molding, the aftermarkets usually have cut and glued corners and will leak, usually immediately.
Check for rust under the gasket -- it will have to be fixed before a new one is put in or the new gasket will leak.
The gasket is one piece (huge!) and the chrome (actually aluminum) trim strip snaps into it to lock the window in place. Not a big deal to replace if you have the suction cups to hold the windshield in place while you get the gasket over the edge ----- ! Usually use a piece of small diameter rope to force the seal over the window -- sounds complicated and isn't, but it is also rather easy to break the glass, so have it done. Just don't let anyone use vulcanizing sealant on it, it doesn't need it.
An independed MN shop will be able to do the installation, or will have a prefered auto glass place to recommend.
An yes, you can buy me a beer! Or I'll just drink one next time I'm out!
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!