Mercedes Benz repair: a/c refridgerant conversion, r 134a, shaft seal

Question
i have a 1969 mercedes 280 se m130.  how difficult is it to install the conversion kit for the refridgerant?  do you know where i can get instructions?  i am purchasing the kit from autohausaz.com.  all it is are the connection fittings and a bunch of o-rings.  i just dont know where all of the rings go and do i need to weld anything when i install the two fittings?

Answer
Do NOT convert.
You loose 25% of A/C cooling capacity if your system is in perfect condition.
To convert, you need to replace all O rings and compressor shaft seal to R-134A compatible material.

Replace O rings + compressor shaft seal and it should be good for another thirty + years with 100% R-12.

Take this test, then you can buy R-12 online for roughly $14.00 USD per pound...
http://www.macsw.org/certify.html
Section 609 Refrigerant Recycling and Service Procedures
for Automotive Air Conditioning Technicians