Most auto glass shops should be able to get them. My buddy just got a new one for his '73 last summer, along with a new windshield...
im an autoglass technician ...22 years now any local glass shop and get them for you i got mine for 50 doallars my cost of course ... usually they go for about 70 - 90 bucks if you can try and find youre local pilkington glass distrubution center ..they,ll have them in stock usually or maybe a one day wait and you might get it cheaper than at a regular glass comapny