I'm finally getting around to replacing the rear shocks in my 07 G35S with 4WAS. All the aftermarket vendors say they don't have a shock for this car with 4WAS. Inifniti parts all show E6210-JU42A or E6210-JK02A as well as E6A10-JU40KNW, both of which seem to fit an 07/08 G35 with and without 4WAS/HICAS.

I went ahead and got monroe for the rears (probably should get kyb instead but these were in stock). The compressed length and extended lengths are different from OEM by about half an inch. The mount point is also slightly higher than OEM and top nut threads are slightly longer. That being said, it does "fit".

Should I be concerned about the piston length difference? I did compare specs to the KYB, and the KYB seems to be slightly longer than the monroe.

 

You should not be concerned. I have a sedan 4was and I'm using 370z Nismo rear shocks which are the shortest lenght overall and not issues whatsoever. I actually looked for a shorter lenght shock to have better action in the shock while lowered.
In reality a shorter shock should produce better performance in theory as long as it's valved correctly. I noticed and could be due to the NISMO aspect of the shock that bound was a bit more firm and slightly bouncier but at the same time I'm using shocks valved for a coupe in a sedan + Nismo shocks have been documented to be very firm from the accounts of the Z crowd.

Keep in mind if you plan on lowering the car camber and toe will be out. If you plan on using camber bolts on the 4was unit the G37/370z SPC will be too short. I created my own using parts of the G camber spacer and a camber bolt from a 2003 Audi A4 which worked.

 

appreciate the feedback. These were slightly longer and I would've been happier if they were a bit shorter, I think. I don't intend on lowering the car. I just have developed a bit of shimmy/roll when going over bumps and have decided to start going through the suspension to replace anything worn or too old. Putting the fronts on later this week, and checking for worn ball joints/bushings/bad tie rod ends, etc... with 175k, i'm certain there's something worn out...