Tractor Repair: Bad oil leak, shaft seal, output shaft

Question
Hi,
I have a 1987 Toro 8hp rear engine ridin mower with a Briggs engine.  The problem I'm having is that there is a very bad oil leak.  The oil appears to be seeping from the engine area onto the (left side) of the deck on the rider.  I think it is the gasket that mounts the engine to the deck, but a friend said it may be an oil seal.  How do I determine which it is and if I need to pull the engine the steps to do so.  Thank you for your help.

K. Holt

PS feel free to e-mail me if you need more information.

Answer
As far as I know there is no gasket that mounts the engine tot the deck --- the engine is a self contained unit -- There is however a seal areound the shaft that drives the deck --- output shaft seal --- this will cause a major leak -- you must remove the engine from the unit in order to repair.