New member here, so I don't know if this has been covered before.
I've found a replacement for the original 280Z 280ZX AAR that works much better, is relatively cheap and best of all it's from Nissan. No more Toyota Cressida valves!!
Nissan part # 22660-45P00. These are off a Z32 300zx/early Infiniti J30 and will bolt right on to any 280Z or ZX. One slight modification is that the terminal locating tab on the electrical connection is slightly offset from the original. It's not needed. 5 minutes work with an X-Acto knife or file to remove it and you're done.
This is a new style " Rectangular " model that can be easily disassembled for cleaning and has a composite slide plate that resists sticking. A much better valve than the earlier " round " style. Bolt pattern and hose size is exactly the same as the original 280Z AAR.
I've found new OEM Nissan ones online from about $75 - $80. I lucked out and found a BNIB 22660-45P00 for $29.95 on E-Bay. Good used ones are plentiful as well as are aftermarket. Standard Motor Products carries them as Part number AC366. Rock Auto stocks them.
Measured resistance is 75 ohms.