I had my 92 300E A/C converted to 134a in 2002. At that time the shop rate was $40.00 per hour. The total project cost me right at $2,000. The shop manual called for 20hrs labor. I had to put in a new evaporator, dryer and hoses in order to use the 134a. My entire dash was removed in order to do the job. I could still get R12 but it was VERY expensive. Good Luck.

tarheel75