parts source

im looking for a good cheap full gasket kit for my slant six everywhere seems to be about 60-70 bux for a full kit. But checking all over E bay im seeing sb full kits for 40 i would think the /6 kits would be cheaper, also can someone tell me if the /6 uses the same filter(oil) as sb/bb mopars do? thanks sorry for such a newb question ive searched all over and cant find an old post.