After my last trip in to the hills, my crate 350 seems to have developed a fairly significant oil leak. I'm hoping it's just leaking out the back of the pan, but it really looks like it might be the rear main seal. My question is - how hard would it be to fix either problem? After some reading, it seems like I can jack or lift the engine up in order to remove the pan and replace its gasket...but I'm unclear if I can replace the rear main seal without removing the engine from the truck? Is there an easy way to tell if the main seal is bad? Also, how involved would either job be? I've rewired/replaced/serviced almost everything else in various cars and trucks I've owned, but I've generally left the transmissions and engines alone. If I do end up tackling it myself, would a jack underneath the pan be sufficient/safe to lift the block with, or would I be better off investing in an engine hoist?