Rear valve cover gasket won't go back on unless I put the seals in backwards. With the front valve cover, I could put a screwdriver around the seal to wedge it over the tube, but it's harder to do that in the back

The brand I'm using is Victor Reinz, made in Japan. One side is flat and says Made in Japan on it. The other side has an inner ring and an outer ring.

Pic attached

 

Good you got the original spark plug tube seal that nissan sells and you also have them installed correctly as you did in the picture.

 

The install you show in your photo is correct ... as has already been pointed out.

If you're having trouble getting the seal seated onto the tube when you set the VC, apply a little Vaseline to the inner orifice of the seal (around inside the hole).

It'll help the seal slip onto the tube.

 

The seal that is in the valve cover is backwards. When the seal is installed in the cover, it should look like the loose seal.

Frome post - https://maxima.org/forums/5th-genera...ervations.html

3rd photo down is the cover as it was removed the engine -

 

Yep ... total dumb-a**es.