I drive old cars as daily transportation so I understand where ashers
is coming from. I'm also a realist. Post War cars offer the best
candidates for true daily drivers.They work and operate pretty much
the same as modern vehicles. There won't be any surprises for a modern
driver with most cars of the 40's -60's. They have enough power for
modern traffic, hydraulic brakes, optional power steering, braking,
etc.

I would choose a popular make (e.g. Ford or GM ) for a daily driver
simply because parts are easier to locate and after-market accessories
are generally abundant.

Another disadvantage of a 6 volt system is that nobody else out on the
road can give you a jump start if you need it. Ford introduced a 12
volt electrical system in 1956. If you want to add ac, whether modern
or period, that's a good year to start. If you wish to keep the truck
"stock" an ac system from a Ford car of the same vintage will
generally bolt right in. Automatic transmissions are also available.

Moving into the1960's, depending how much money you wish to spend,
well appointed trucks are available with just about every option a
modern truck would be expected to have.

As for air conditioning, unless you find an old truck that already has
a good functioning system, I would forget about trying to locate a
period unit. I would install a complete, modern 134a system from
Vintage Air http://www.vintageair.com/ or Classic Auto Air
http://www.classicair.com/ . Both of these companies make excellent
products and will custom tailor a unit for your application. Another
advantage with one of these retro-fit systems is that the compressor
and other components are smaller, lighter and more efficient than the
original systems of the 50's and 60's.

Unless you really enjoy working on cars and have an above average
desire to do so, don't bother with a prewar car, especially one as old
as a Model T. They're nice to look at and probably fun to tool around
town in on Independence Day but to rely on one for daily use is asking
for trouble. Even a Model A, although "reliable" by the standards of
1930, is no match for the average modern driver. Why would you want a
car with mechanical brakes, skinny tires, and limited power. You are
asking for trouble and they just aren't safe on crowded streets,
especially in bad weather. It may look "quaint" to make your
deliveries in a 1930 woody or pickup but that quaintness would soon
wear off and simply become an annoyance.

If you live in a town like Mayberry (with as much traffic) and don't
have to deliver goods more than a couple miles from your business, a
Model A might suffice. If you live in a normal town, I would
concentrate on vehicles from the mid 50's through 1979.

Forrest