While many airplanes use a mount that attaches at the rear of the engine and connects the engine to the firewall, the Cessna 210, and many other light airplanes, use mounts under the engine; the airframe forms a reinforced cradle beneath the engine and it's actually bolted down to the frame on shock mounts, rather than using a tubing frame assembly behind the engine.
The installation gives very little clearance beneath the engine for changing oil or doing anything involving the oil pan area, and it's a pain in the butt when dealing with a leak or spilled oil. The whole engine assembly is fairly tightly cowled on the 200 series Cessnas (except the 208, of course). There's not much room behind the engine when working, either, which can lead to spills when changing the oil filter, and so forth. Where some light airplanes have a lot of space inside the nacelle or cowling, the 210 doesn't.