The Mini went through 3 official generations. They were the Mk I, from 1959 to 1967, the Mk II, from 1967 to 1969, and the Mk III, from 1970 to 2000 (and used for the new BMW MINI).
These cars all had I4 A-Series engines of varying size. Transmission options were the 4 speed automatic and 4 speed manual.
There were several body types for these cars. They included the saloon, estate, van, and truck. I can't imagine the Mini truck doing much heavy work. Perhaps it was used on a little person farm. That's something I'd pay to see.
The Mini Cooper and Mini Cooper S were sporty performance versions of these cars. Thanks to their light weight, it was only a matter of fitting a more powerful engine and upgrade suspension and handling parts to make this car a viable racer. A special version of this car won the Monte Carlo Rally in 1965.
These Austin / Mini / Morris cars are very popular with collectors. If you own one of these cars, there are literally hundreds of car clubs that would be glad to have you as a member and take a look at your car. If you'd like to own one, try looking at the eBay listings. There are lots of good deals on there, and also plenty of parts.