I'm currently running a R 200 with 4:11 gears and a quaife unit. I'm needing lower gearing. What are my options? Quick Change? Nissan Motorsports VCLS ? Along with your input, please include sourcing info. thanks.

4.38 gears came in older (R32?) Skyline, OS Giken makes a few sets that are $1500 I think. John Coffey could probably hook you up with an OSG gearset if you wanted to go that route.

Quick change is an entirely different differential. They're definitely cool, but they are long and I don't know if there is room in a Z. You'd definitely have issues with the rear brace across the rear control arm bushings. If you really want to change the diff and you don't need to change ratios from track to track, I'd go with a Ford 8.8 IRS. Gear ratios from 2.71 to 6.14, helical LSDs are about $500, stronger and lighter than the R200. Only bad part is you'll need to figure out axles and mounting. I can sell you gears, install kits with bearings, LSDs, and even bare housings through www.m2differentials.com. Probably easiest to go get one out of an Explorer (31 spline axles vs car 28 spline and has an aluminum housing) and then buy the parts from someone like me.