He said about 1K (which would be a proper upper and reinstalling the gears)..Looking at the casting of the upper compared to where the check valve is, it doesn't look like you can tap into anything... https://www.flickr.com/photos/135073.../shares/3wj32L

That sucks. I would still want the reservoir. Without it you won't know if you have a problem until the drive blows.

Your other option would be installing a drive temperature sensor in the upper vent hole. It's a really good thing to have.
But I too would want the proper upper. You can sell the old one.

You can still do a gear oil reservoir as a hose connection will install in the vent plug screw in the upper outdrive. That hose then will can be installed thru the transom ( hole drilled ) and the reservoir mounted in the engine compartment or engine side. Not hard to do at all. This is how it was installed as an option when the bravo first came out that offer no gear oil reservoir

Next I do have all new made kits of temp gauge / oil temp sender that installs in the outdrive for monitoring its temps. The gauge can be set to a desired temp to show a red lite warning as well along with the analog temp reading numbers displayed. I am not ready to bring it to market as I wanted to test it for a full year of boating but have not been able for 2015. FYI

here is the reservoir kit I am talking about. We use to install these way back years ago even for Alpha one apps'

Merc part number is 525-69622a7

http://www.cpperformance.com/p-67706...r-69622a7.aspx

I'd change the upper case out.

The older cases have a void cavity where the check valve would be. Could run a line to the vent plug

Some good info guys, thank you for the feedback.

Might just go with a proper upper case, if I can find a good one over the winter layup. I always think that proper preventative maintenance is key to longevity (especially with a bravo) and I just hate the idea of not using the reservoir.