Super big thanks to Dane Miller at Houston Z Auto for meticulously and patiently fitting Z32's ABS unit into my R32. Also big thanks to Omnigear for his keen observation on the similarity of Z32's ABS unit. Now, I can't guarantee that everyone will get the same result, nor can I guarantee my resolution will be permanent, but it sure beats filling the entire brake fluid reservoir once a month.
I bought an used Z32 ABS unit for the 2+2 trim, OEM# 47600-32P00. The unit appears to be in great condition given the low cost of $35 shipped. The unit for a Z32 2-seater, OEM# 47600-30P01, looks to have the same exterior dimension and I believe it will fit as well, but I picked the 2+2 because R32 also has 2+2 chassis. Z32's units will most likely be in much better condition because they are either mounted in the trunk or behind the seat, as opposed to R32's being mounted in the engine bay.
After the R32's unit is removed, here is how it compares to a Z32 unit. Z32 unit has white plugs with relay housing mounted directly on top of motor with no adapter for the brake inlet lines.
And this shows how bad the leak was. The paint is pretty much ruined.
After the 2 relays are removed, the plastic housing can be seen secured to the metal bracket below with 3 screws. After removing housing the metal bracket can be removed, which is an offset bracket and will be used on the Z32 unit. During this step Dane realizes there is a chance that he can swap over R32's oval plugs without cutting and soldering. So a change of plan.
Here is a tip. Jam the thin metal pick into the back side of a plug and its metal bracket, and the plug will come off smoothly. And for reference, here are the pin-outs of the ABS units for R32 and Z32.
So, the 6-pin and 2-pin plugs are attached to the plastic housing and can be transferred to Z32 all together. The 4-pin plug however has the 12v source attached to housing while the other 3 attached directly onto the ABS unit. Using the thin metal pick, the 12v wire at lower right of the plug can be de-pinned. Dane de-pins the 12v wire off Z32's plug and finds both units use the exact same pins. So even though the plugs have completely different outside shapes, internal dimensions are exactly the same, down to the tabs holding the pins.
So now Dane has the confidence to de-pin remaining 3 pins, and soon all 3 oval plugs are off R32 and onto Z32's ABS unit. Next step is to take off the 2 metal adapters for inlet brake lines. Once they are off an obvious issue arises. R32's unit has 2 alignment holes, but Z32's is completely smooth. Now at this point there are a few options, grind the alignment dots off adapters, drill new holes on Z32, or the lazy man's option; just flip over the adapters. Well, I have never been the overachieving type!
Here we are, plugs swapped, housing mounted on the offset bracket, and adapters bolted. Looks just like a R32 ABS unit!
To finish the job off, nice Motul 5.1 goes in for the brake bleeding. That Z32 unit must have been sitting for years, because the crap that came out of it is just unreal. The "Crystal" logo on that plastic cup is especially ironic and funny.
I will report back once in a while to let yall know if this Z32 unit continues to hold. After all it is off a 1992 and only 2 year younger than my 1990.