The new disc brake setup is much more beefy than the OEM stuff. I used the 5x4 kit because I didn't want to buy new rims for the car. However, to answer the other part, no, the stock upper ball joints will not fit in the new spindles. They have the holes for the larger B Body ball joints, and the original control arms have the smaller size. Assembling it was extremely easy. Once you have everything ready to go, it takes about 20-30 minutes per side. Don't forget to torque the bolts as you go. I forgot on one side and had to disassemble it just to torque two bolts. Even then, it was quick. Here are the links to the stuff I bought. I also used the Jegs promo code and got the kit for $587