Sept. 11, 1987 build date. Made for the 88 model year, built 2nd shift, "C" seems very light stamp in front of ZF as it's not supposed to have any gaps after the model year. Probably filled in with whatever paint they were using. And 0546 is the unit serial number.
Unless you're going to put a Chevy engine in it, stick with the OZ. It's just as good.
IMO, when the OZ is set up to factory specs, it shifts harder than a CZF, so if you're looking for a softer shift, go with the CZF.