freon

I would like to find r12 substitute for my old a/c system.
Local stores in the LA area pep boys, auto Zone, etc, say I need a
license to buy the environmentally safe stuff, yet is available online
with no such requirement.

Questions:
Are there really any restrictions on the e-safe stuff?

How do I get this into an old system? All the new cans appear to be
the r134 screw on type, rather than the puncture top cans.
I don't want to replace my valves because my old type pressure gauges
will not work with the newer valves.

What I would like is a filler hose with the newer type tap end for
the can, and an attachment that can be used to fill my existing system
thru the original valves on the compressor. This would enable me to
use R134 leak detector, as well as envirosafe, or some such similar
product to recharge the system.

Any suggestions?

Thanks


Tony