90 Lebaron AC port size High Side

90 Lebaron 3.0 V6, I need to locate an adapter for AC high side port so I can connect it to a R12/R22 manifold hose and guage set. Hose sizes are 1/4" which also is low side port size, but high side port is smaller than low side. ..... Anyone know what size the high side port is and where I can buy an adapter to allow connection to R12 size hoses.
..Thanks Guyc400