I am needing to replace the gears in the upper housing of my drive it has no forward gear only reverse. My question is do you seperate the lower unit from the upper? Or can I just pull the complete drive off and replace the gear with the lower unit still connected to the upper?? Thanks for the help guys and girls in advance.

In theory, you could....it will be a MFer to handle though.

Generally, when something ( gears, bearings)has taken a dump in a drive, you'll need to fully disassemble it and clean the crap out of it.

Ok thanks for the reply im hoping its not to big of a mess. Again thanks.