In the Tiger E, the front of the engine was bolted into the firewall. The rear of the engine had two feet. These feet stood on two posts welded into the floor.
This is the left-hand post in the Bovington vehicle. (This is not the original German paint.)
Each post was close to a strut on the hull floor. A ramp was built between the post and the strut, to guide the engine into place when it was being lowered into the tank.
This extract from a German drawing shows that the posts were behind the rearmost torsion bar.
This plan diagram shows the posts from above.
The engine was held in place by long bolts running through the posts. The heads of these bolts were in 12mm-deep recesses in the belly plate.
[1] Survey of vehicle 251114, at Saumur, by Jean-Charles Breucque
[2] Survey of Tiger 250122, at Bovington museum, by David Byrden