Earlier, Hank Nixon wrote:

A little research would show the 2-33 was introduced in about 1972...

Heh, and a little more research would show that the 2-33 actually
dates to five years earlier, in 1967.

The original 2-33 was certificated on 10 Feb 1967, followed by the
2-33A on 7 March 1968 and the kit version 2-33AK on 19 April 1973.
When I worked at Sky Sailing in the early 1980s our 2-33 fleet had
several pre-A models in it, so there was definitely a substantial
number built prior to the Feb 1968 A-model introduction.

Here's the TCDS in .pdf from faa.gov:

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/84b126f9575b545d85256721004ee3d9/$FILE/G2ea.PDF

(Would you like TLAs with that?

Personally, I like the 2-33 as a basic trainer because its simple and
rugged, with lots and lots of crash-protection iron. Bill has a point
that it is a distinctly unsexy aircraft. However, in my experience
rugged unsexy trainers outperform broken trainers on most days of the
week.

Thanks, Bob K.