The rear main leaking is common when they get older. You may want to trailer it home if it's leaking bad. I bought one that was leaking a solid stream from the bell housing. That explained the 3 or 4 cases worth of empty quart oil jugs in the box.
Check the front cab mounts from below, they rot thru and drop the cab. The floor may be gone too, mine rotted from the floor down and took out the mount.