dont know if anyone knows this but, if you do thanks for letting others know. a buddy gave me a set of 3.73s from his 8.5 rearend. well i was told the pinion bearings are the same for the 8.6. and they are......... up to 05 but for some odd damn reason gm decided to change it for 06-07 classic. so, i ended up buying a bearing and race for the pre-05 ( dealerships didnt have the correct bearing) and it works great. just wanted to let others know so they are prepared and are not suprised when they have to spend all day looking for parts.