Differentials ready to bolt in. Built to order. All are fitted with new bearings and seals. These are blueprinted and guaranteed to be within OEM specifications. Diff Lab's target blueprint specicifations are much narrower than BMW's specifications, so you can be assured you're getting the best build every time. Builds can take 1-3 days. If the job is urgent, please let me know. Motorsport gears can have ~10 days lead time. Just add one of these items to your car along with the LSD you'd like, and the gear set you'd like. It will be assembled for you and delivered. All differentials are exchange units. An exchange differential must be returned to Diff Lab within seven (7) days of receiving your new differential. A core charge is needed, and is refunded after your differential has been returned.