Got a 78 Chrysler 115hp and about the change out the impellar.  Never worked on a boat motor before so i bought the service manual.  I'm a little nervous since I'll have to drop lower unit and go so deep into motor to get to water pump.  Anyone got any tips for a first timer?  Also, I know I'll have to replace any gaskets on my way up to the water pump, but what about seals?  According to the manual there are seals and gaskets.  I'm assuming the seals are rubber and may be reused if in decent shape while the gaskets are certainly paper and will be destroyed in the process.  Any ideas on what all gaskets and seals to be prepared to replace in this project?

If you have a service manual, it should list everything needed for the job.  Replace all seals and gaskets.

x2 on the replace all seals and gaskets. they're cheap but labor isn't, even if it's just your time. you don't want to have to rip it all apart again due to a $5 seal.

I'm pretty comfortable with the process now...I looked more at the manual and I won't have to get into the gear housing at all, the water pump sets on top of the upper gear case cover.  There's only a couple seals and 1 gasket.  Ordering them tomorrow.

Don't put anything in there that it doesn't say to or come with in the kit.  Something coming lose and plugging the "pee" hole would be bad.