You need to drop the oil pan out the bottom.
You do NOT need to remove the Q45 VH45DE engine.
But, you do need to unbolt the two motor mounts.
So you MUST support the engine from above!
Otherwise, you'll be crushed when you remove the front crossmember.
To remove the front crossmember the suspension links come off.The transverse link must be removed to access crossmember bolts.Leave the steering rack hanging once you remove the crossmember.
Mechanics can do this in a day.
DIY will take a few weekends as you're essentially removing the engine.
Most of the time you also have to remove the front engine gusset.
That adds about 5 more hours to the job.
That's because the alternator & compressor are bolted to the gusset.
The fan and all the belts have to come off to unbolt these two units.
Remove two rear engine gussets and the flywheel plate.
Support the transmission but leave the transmission mount intact.
You also have to disconnect the steering u-joint just above the rack.
While you're there you may as well replace the two engine mounts.
Also replace the two steering rack bushings while you're already there.
Some replace the alternator while they have it out.
You do not ever wish to remove an alternator after once doing it once.
Only 18 bolts hold the Q45 oil pan onto the engine.
While you're there look for chain guide parts in the oilpan.
Almost all 1990 to 1993 Qs will have lost their chain guides by now.
You can get a kit from Joe at Scottsdale (http://www.everythingnissan.com).
They are the best price Infiniti parts dealership in the world by far.
If you don't replace those guides you will lose your engine eventually.
Timing chains slip teeth & valves tap dance on your piston head.
Guides & oil pan almost always come in pairs.
Button it all up with RTV red & locktite red and you're all set.
Simple.
