So I'm getting close to upgrading to strange disc from my 11 inch drums on my strange S60 rear. They offer 2 mopar housing ends for the S60 rear and since I retained my drums when I got the rear I am assuming I have the smaller factory end. Question is,the kit they sell for the factory housing end comes with ball type axle bearings and is more money than the kit with Strange ends.Why is that,and do I have to use them? The rear has been in the car for a while and I believe has green type bearings.