suzuki df175 2008 drive shaft parts ex.bushing

[TSMBC277]

Hi All,
I would like to know what parts like o ring, spacer, shim that go above and below a suzuki 2008 df175 drive shaft bushing or drive shaft bearing.Is the drive shaft bushing the same as a drive shaft bearing? I have a small oil drip - 4 or 5 drops of oil-coming down the drive shaft bushing.
It appears that someone installed a oil seal under the drive shaft bushing.Is this normal?-- what purpose does this serve if in fact its not a factory installation? and is the small oil leak acceptable?
thanks,

TSMBC277

[boats.net]

The drive bushing is in the mid housing and has no seals, no oil in mid section. The drive shaft bearing is in gearcase but is below drive shaft seals.