I have an all-window 1968 A-100 8-door.
I haven't kept as much recently, but the vintage-vans site had about 10 8-doors total. Pretty rare.
As far as actual production numbers, it's the same story as the muscle cars, nothing available with breakdowns.
The sweptline site has production numbers for basic numbers, I posted them on the VV site years ago.
In my case, a 68 shorty with V8 auto was about 2600 total. That is panel, display, all window and the 8-door and no side door variations all lumped in.
basic info
http://www.sweptline.com/hist/a-100.htmlproduction numbers
http://www.sweptline.com/hist/prod_info.htmlThere are a bunch of other sites with some pictures and general info. Be aware that most people will repeat the info from other sites without questioning it. Lies get repeated...
Best bet is to get a service manual and try to find a parts catalog. I've run across both online at one time or another, but they often disappear after a while due to sites closing and/or takedown requests.
They are dead simple in most things, but some parts unique to them are hard to find. Electrical, cooling and steering are the main things to check out.
There have been some reproduction parts lately, so that's nice. Shop around, most are available thru many sources.
EDIT:
I see the auto shifter on the dash, can't tell if it's a 6 or 8 from those pics. It's NOT a 108.
1966 Truck Production
Model Wheelbase 6-cyl V8
A-100 90" 35,190 9,536