Either the 600 or 800 series box.What steering box comes stock on a gbody? Specifically a mid 80's monte carlo.
Box ratios vary depending on engine and options
Also the box alone does not determine overall steering ratio, the linkage also comes into play
I suggest you download the info packet from https://gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.html for the specs on your car as configured
As an example of the variables, in 1980, Malibu steering box ratios vary from 24.0:1 to 13.0:1
How about the box with the Z stamped on it?
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