On my 90 Nova with 454mag how many fittings should I be looking for and how much should I give them?

Your best bet is to pull the drive, inspect and grease the splines, u-joint etc...

Two on the back of the engine coupler, one on the side transom mount for greasing the gimbal beraing (10 pumps on a grease gun to lube that bearing), two on the U-Joints.

Gotta pull the drive like Panera said, to get to those two on the U-joint. If you pull the drive then you can grease the U-Joints and the input shaft spines without having to use the two fittings on the back of the engine. Also allows you to make sure there were no leaks around the O-rings. Worth the 15 bucks to pull it if it hasn't been off since last season.

Had la eak a few years ago on a Baja and had water coming out of the shift cable in the engine box. Was a pinched O-ring...cost me some cash to get that cable replaced.

Go to your closest Merc dealer and obtain the correct grease for th splines and gimble bearing..

I had the drive pulled middle of last summer and greased and check out at Burgers Marine at loto down by the dam. What I was wondering should I hit the grease fittings. Looks like one one the back of the bravo out the back and two that I can remember inside.

On my 1988 Bravo 1, there is a grease fitting on top of the drive as well as the one on the starboard side. Your 1990 may have this also. Those plus the two (you only need to get to one) on the coupler and you are done if you do not mind skipping the u-joints this time.

If you have a West Marine around they carry the Merc grease and o-ring kits.

Do you need to replace the orings every time or just if they look worn?

How long does the shifter boot last untill it starts leaking? Mines 5yrs old.