This is the flange that attaches directly to the pinion shaft of the rear differential on your WRX or STI, and bolts to your propellor shaft.

The bolt pattern is different between the WRX R160 differential and the STI R180 differential, so if you are doing a 6-speed swap, this part may be helpful.

The Subaru Part # for the WRX Flange is 38358AA000

The Subaru Part # for the STI Flange is 38358AA040

Please note that we can not guarantee fitment if you are not using this part for the application it was origionally designed for, and once it is installed, it is not returnable.