1991 rx7 stock convertible, non turbo. I unbolted my rear suspension subframe , brought it down to ground, put it back up without changing anything. I noticed a gap between back rear mounts and subframe when I jack differential up so the big bushing meets frame of car. Is this gap normal , for steering around corners , etc? Wheels are off , car is jacked up on stands, front mounts on rear suspension subframe look fine, no gap, bolted in and torqued to specs. If I lower jack holding up differential, the subframe lowers onto the mounts but the gap is now between car frame and those rear bushings. Bushings heights look normal even for car with mileage, but maybe I’m incorrect and it’s worn or need a spacer now? I didn’t check but perhaps this bushing is a bushing with space to allow sideways movement, whereas the front do not?

 

Here's a photo of my right rear differential mount when attached to the car's underbody. These mounts should be relatively tight and without the large gap that you're showing.

 

It may not be the case for yours, but when I redid all the bushings on my rear subframe a few years ago, those mounts were sort of cupped down from getting banged around for decades. I put mine in my press and squished the steel disc back to flat. That closed the gap on mine.