G'Day Dave,
Your right

as regards the 101 numbers .... I spoke to a few people who are into FC101's and I always had in my mind a figure of 3500, but they pointed me to these figures:
956-Series 12v RHD Home (British) 1322 Units
957-Series 12v RHD Export 28 Units
959-Series 12v LHD Export 583 Units
961-Series 24v RHD Home 170 Units
962-Series 24v RHD Export 92 Units
964-Series 24v LHD Export 474 Units
Total 2669 Units
As regards the Pinny figures..... hmmm, I agree the figures don't always stack up but there is a lot of misleading information around.
I'd love to know the absolute truth, but like any industry associated with the military there is always a degree of secrecy.
Steyr Daimler Puch were pretty good in talking to "enthusiasts" and supplying information, but as mentioned, like all companies with military links their were always "no-go" areas.
(However I had/have a fair few contacts that were helpful in supplying information)
Automotive Technik were less inclined to talk to "enthusiasts" and even more so after S&S/Armor got involved!
(Contacts were few, althought at times a little information trickled out

)
BAE are a "tell em nothing" type company and the little bit of information that does escape is pretty lightweight and usually PR stuff that has been mulled over a thousand times
So given the above, here are some "stated" facts that can be referenced to written sources:
1967 – 1985 710/712 Pinzgauers 18,369 Pinzgauers built (Puch-Automobile 1900-1999, Friedrich F Ehn)
1985 – 1990 716/718 Pinzgauers 1826 Pinzgauers built (Puch-Automobile 1900-1999, Friedrich F Ehn)
Therefore:
1967 – 1990 710/712/716/718 + Hybrids 20,195 Pinzgauers built (Puch-Automobile 1900-1999, Friedrich F Ehn)
1967 - 1999 710/712/716/718 + Hybrids 24,000 Pinzgauers built (Steyr Puch - 100 Years, SDP)
1967 - February 2000 710/712/716/718 + Hybrids 24,000 Pinzgauers built (Puch, Egon Rudolf)
"More than 30,000 Pinzgauers are in operation today" (TVS - Stewart & Stevenson Brochure 2006/7)
We could split the TD models down further as you have eluded too, but that can be for another day
.... then there are the "maybe" correct statements by some generally pretty reliable sources such as:
In Oct, 2002, Janes Weekly stated "30,000 vehicles for 24 countries over nearly 30 years"..... yet after researching Janes own specific military vehicle publications (and other sources) that list countries, I can't come up with that many recipients, so is there something in this statement that possibly points to other uncounted vehicles?
....and finally we have the unsubstanciated rumours (and that's all they are) that:
Unknown quantities of Pinzgauers were sold to Syria in the 70/80's ... and possibly other various counties.
A lot of the above are really just smoke and mirrors but they do add intrigue to the numbers debate, however I heard the 34,000 figure from a "contact" in Europe not that long ago (unfortunately I don't want to mention his name) who like us is intrigued by the figures so maybe in the future at some stage more solid evidence will come to light.
I guess we can say it's somewhere between 25,000 (? You said lower than 26,000 Dave) and 34,000 (?)
BTW Dave, I understand AT had a production rate of about 10 Pinzgauers per week, so I guess your figure of about 500 vehicles a year is within the ballpark!