Replacement product for Air Conditioning R-12 freon

[10558372]

I have a Arrow IV with Air Conditioning, which works well although a small leak somewhere in the system requires a small recharge every summer. R-12 which is the factory spec is very hard to find and expensive.
What experience out there with other freons, modifications needed, cooling efficiency, etc.

 

[flyguydon]

 

[TEG916]

 

[Tweety]

 

[pirate40]

 

[Tokirbymd]

 

[jacobsja]

 

[sccpc]

 

[Tweety]

 

[Ray93J]