I found a small leak in my radiator, and decided to remove and repair. As the condenser has seen its share of dings, I am repairing/replacing as well. I had the A/C system evacuated, and removed the lines to the condenser, as well as the filter/dryer and high/low pressure switch. As I removed the various lines, I see 'O'-rings on the ends of the various lines. Where might I get the specified sizes for these various o-rings? Is the material of concern in the R-12 environment? I could use the old rings as templates, but they have been stretched over time. Any help concerning these O-rings and material is greatly appreciated. I assume that since the system is now open to atmosphere that I must replace the filter-dryer. Is that correct? Thank you. Jim S.