How rare is this and how much is it worth?

[silverado76]

This 76 Suburban Silverado Estate 2WD 350cuin has been in my family since new. It has 131K miles on a completely original numbers matching powertrain and body. It has never been painted other than touch ups. I have the original hubcaps but I dont drive with them because they are not available from any aftermarket supplier and so I don't want to lose them.
It is a full 3 bench setup but no air or power anything. Everything works including the radio and the clock. The interior is decked out with added trim details around the door panels and dash along with the obvious extra woody mactac on the exterior.

What I was wondering is if anyone knows where I can find out how many of these estate packaged burbs were built and if any still exist. They were a factory option at the time. Also if anybody has a ballpark what one of these might be worth these days, that would be great