Was the Dryer an NOS part or was it supplied by Classic Air? he deal is 70 style switch & dryer were whats known as "o" ring boss.. 71 is 1/8" pipe thread... The easy way would be to just let an A/C shop provide the switch, they will be able to see what you have & match it functionally.. Visually it may differ a little but if you've converted to R134 then chances are it already has different charge ports...