thrusts exerted upon it a lower oil seal housing 34 is affixed to the lower unit 14 and carries a lower oil seal 35 that sealingly cooperates with the drive shaft 24 for sealing the lower portion of the lubricant cavity 33 the seal housing 34 is also sealingly engaged with the lower housing cavity 14 so as to insure a good seal at the lower end of the lubricant cavity in a similar manner an upper seal carrier 36 is affixed to the lower unit 14 and carries a seal 37 that is sealingly engaged with the drive shaft 24 at the upper end of the lubricant cavity 33 and above the bearing 31 a combined fill and drain passage 38 extends vertically downwardly through the lower unit 14 from an opening that is normally closed by a plug 39 to the lubricant cavity 33 when the outboard drive 11 is in its normal operating condition the upper end of the passage 38 is disposed vertically above the cavity 33 so that lubricant can be added to it in addition an air vent opening 41 which is also closed by an appropriate plug is provided at the upper end of the lubricant cavity 33 so as to insure complete filling when it is desired to change the lubricant within the cavity 33 the outboard drive 11 is pivoted from its normal running condition to a tilted up out of the water condition normally the outboard drive may be tilted through about 60 degrees u03b1 under this condition however in order to facilitate servicing it is desirable if the opening 38 is disposed so that it will be positioned at the lower end of the.