Bell housing. Done it lots of time on a Mazda, where modifications required lifting up the engine to change the oil filter... Back then, we only had the standard OEM jack-knife jack, so we actually raised the car at the normal point, then lowered the car with a brick (clay brick, not Volvo) under the bell housing. When I got my 144, I bought a hydraulic trolly jack which grips nicely on the edge of the bell housing. Have not done this on my 240, but did it last Sunday on my 144 to replace the mounts. Much better than trusting a piece of wood to spread the weight over the pan, especially if you accidentally jack up too far without realising it. Whichever way you do it, just see that the exhaust does not push against anything that could cause a leak.