orgazmick

hi chaps just noticed oil drops on the bottom of my engine at the where engine meets the gear box .the strange thing is the oil is a thick black oil but smells like gearbox oil .but how come it's black .ive checked all the oil levels and they seam fine not high /low but i have only just noticed the oil leak. me thinks it's the gearbox input shaft and thats sound expensive . could i do the job myself i have access to a garage with a fulll size pit any suggestions would be helpfull apart from burning it and getting the money