The transmission hump had been modified before the car went to bodywork for the later transmission. it looks liek this panel was replaced reverting to the original panel.
As a result the transmission no longer fit.
We removed the “hump” portion from between the rear seat from a 1987 Carrera and adapted this to the 1971 rear seat area. After lots of fiddling adjusting, bending, etc we got a good fit. It was then installed with sheet metal screws and an industrial epoxy panel bond (J.B. Weld specifically) was used to bond this in place.
Once the epoxy cures (15-20 hours) this will be sanded and blended, protruding sheet metal screws ground flush on the underside, and seam sealer will be applied from below. Dynamat will be applied over the entire rear seat area as a noise insulator. The underside will be painted to match.