Anyone know what type of high side adapter fitting is used to attach a R-12 AC gauge set to the high side port ? I am still running R-12 refrigerant, so I am NOT looking for an R-12 to R-134a adapter. The standard 1/4 inch SAE flare used on a typical gauge set is only used on the AC low side. The high side uses a special fitting that measures .380 " diameter (which is 3/16 SAE) , but has no flare for the seal. Vendor for typical 1/4 to 3/16 SAE adapter says it won't fix the 87 max .