If it's an automatic, most likely a Turbo 350.
A fusable link.
I think it is 18436572 usually stamped on intake manifold on the old Buicks.
Not sure, but you might find an old Chiltons manual on Amazon or Ebay.
garry G&L AUTO REPAIR
The firewalls should be close enough to work they may be some differences from vehicle to vehicle though
I downloaded the diagram for a 1969 Chevrolet C 10, 350 V8 off the Web but I don't have the Web site address. If you write me I will forward it to you. rbevz@cyberport.net
Most auto glass companies can probably get that for you, but if they can't you might need to start contacting wrecking yards.
NO. The latch system didn't come into play until somewhere around mid 2000's
Probably around 16 mpg. I had a 1969 LeSabre once and the best I got out of it was 18.6 on the freeway.
I think they will. Not 100% sure though.
Yes. I had a 1969 LeSabre in 1980 that still used leaded gas. Any auto store will have lead substitute. Maybe another poster knows if super unleaded is good enough.
A 1969 Buick Riviera sold new for $4,700.