Chrysler 7.5 Mod. 72H9B, Ser. 2959 from what I have researched this is a 1979 to a 1981 model. We purchased this motor about a month ago and boy did she run sweet. Last time up to the reservoir on our 14 ft. john she acted like an automatic transmission slipping. Brought her home and checked lower unit oil and no oil. Pulled the bottom plug and it was cross threaded, so evidently it had leaked the oil out. Filled her back up and she sounded bad when we put her in gear. Was pumping great water flow. Drained oil and smelled burnt. So here is my question, we purchased a reconditioned lower unit for a $100.00. It looks like the other one with a drive shaft. Before we take it apart is there any special tools or any gaskets we need to do this repair? Or is this some thing we shouldn't attempt, and hire a professional? All advice would be appreciated. Thanks ooks.