I found the stock 4.08 final gear combined with the LS1\T56 to be somewhat painful to drive\drift.
With this setup 1st and 2nd gear are completely useless.  3rd gear was good enough to get the car going and 4th\5th gear was where most of the drifting would be involved.  That is a lot of shifting.

Everyones driving style is different but I found going with the 3.54 R&P from a Q45 to be much more tolerable.  The torque from my LS1 is more then enough to rip the tires loose in 3rd gear at 2500rpm so might as well let the gear last as long as it can. 

I bring another pumpkin\LSD with the 4.08 gear with me to the track as it does have its use.

Outlined below are the general steps involved to put the Q45 3.54 R&P into your 240sx with a Kaaz LSD for open diff pumpkins (SAN2655).  It is assumed that you already know how to install a LSD.
Special thanks to Brad D on KA-t.org as being the pioneer of this install.

1.     Drill the Kaaz LSD with a 33/64 drill bit.

o    The Q45 Ring uses 13mm bolts compared to the 240sx 12mm bolts.

2.     Install the Q45 Ring onto the Kaaz LSD and torque it to specs.  Don’t forget some kind of thread locker.

3.     Remove the bearing from the Q45 pinion.  (requires a press)

4.     Remove the bearing from the 240sx pinion. 

o    Note the spacer underneath it.  Mine was 3mm and is the smallest one Nissan provides.

5.     Put the 240sx bearing onto the Q45 pinion

o    A spacer should go under the bearing for proper backlash.  When I tried to use the 3mm spacer the Kaaz LSD outer case would hit the pinion gear.

o    Since Nissan does not provide anything smaller a custom spacer would have to be made.  I opted to use no spacer.  My backlash is out of spec but good enough.  I have a full contact pattern but it is a little higher on the pinion gear then the FSM calls for.  I estimate the proper spacer needed to be 1.9mm thick and could custom order one from mcmaster.com.  One day I’ll take it all apart again and find out the exact size.

o    If you break the bearing it costs roughly $65 - $85 from Nissan.

6.     Place the spacers that were on top of the S14 pinion bearing on to the Q45 pinion with the S14 bearing.

o    What you essentially need to do is to put whatever is on the S14 pinion on to the Q45 pinion.

7.     Put the pinion into the pumpkin and torque it to specs.

8.     Put the thick spacer on the opposite side of the pumpkin.  It should now be on the side with the Ring teeth pointed at it.

9.     Place the LSD into the pumpkin as you normally would.

10.   Place the appropriate shims in, torque everything to specs then measure backlash and contact pattern.

Q45 Left - 240sx Right