Is it possible and how hard is it to install a drive oil reservoir to a 1988 bravo 1 that was not equipped with one.

I installed one on a 1989 alpha, it was a piece of cake. Merc makes a kit (I bought it from BAM) includes all the tubing, fittings, transom seal, bottle, etc. Just replace the vent plug at the top of the drive with a fitting to accept a flared tubing connection, drill hole in transom, install seal hardware, attach tubing inside and out, and voila. I've had mine installed for two seasons.

Ive done my 88's too but I used the dip stick hole on top of the drive so the drive stays flooded. I have some pics I think. I could show you the inside too if you want.

Thanks. I thought it was all done on the in side of the transom assembly

Nope, drive and transom assemblies are different, have to hose it.

Nice job dude!