Doing a Handyman with two Model S DUs here. Measure across the outside of the 3 tires and then across the Chevy, I think you'll find there isn't enough room in the fender wells. Also the frame rails go right through the middle of everything.
If you still want to use the Tesla Model 3 rear drive unit and subframe with suspension, you can check the dimensions with a CAD model. If you haven't used CAD or 3D modeling, now might be the time to start.My questions are will the Tesla unit fit within the stock fenders and where will the subframe mounting pads fall relative to the stock frame rails? I am not concerned about interference with the inner fender panels, gas tank, spare tire well (both to be removed) or trunk floor. I have not been able to find the dimensions that I need before committing to the project. I am looking for 1) the outside width of the stock Tesla tires, 2) the center-to-center dimensions of the four subframe mounting points relative to the rear axel centerline, 3) the height of each mounting pad above the ground, 4) the overall diameter of the stock Tesla wheel and tire combination. Also, are the mounting pads symmetrical with the centerline of the vehicle?