my montero sport has an oil leak at the back of the engine it doesn't look like its the valve covers, and the back of the oil pan is under the flywheel cover and that cover doesnt look like its coming off easy but thats where most of the oil is. just wondering if anyone has had this problem and can tell me if if its likely the rear main or the oil pan

 

rear cam plug "o" rings. VERY common.

 

is it easy enough to do in my garage since its over head camor does the engine have to come out or something