This crankshaft spacer will allow for a RB26 flywheel to be used on ANY L-Series engine. This includes the 4 cylinder L series as well. $40 shipped ANYWHERE in the US. International orders accepted at additional cost to buyer.

The RB flywheel allows for a cheaper alternative for light weight flywheels. You can get a 14.5 lb flywheel for an RB engine for HALF the cost of a 16 lb flywheel for the L series. This also allows you to use a 350z clutch which has 255MM of surface area, versus the 280zx turbo clutch at 240mm. But you can use any clutch from any year Z from 70-Current.

A full detailed technical article can be found here http://forums.hybridz.org/topic/124844-confirmed-l28-with-rb25-flywheel-and-350z-clutch/