i put my car on lift sat. after work to check to the back brakes. found the rear calpiers sezied up, so i put it back together, no parts, but i found the driver side axle bearing has some play up and down. idont know if the axle is messed up or not but should i put better axles in?
i dont go to the track a lot and im only run'in nittos so do i need better ones?
better ones, as in a better 28 spline axle or up-grade to large ones, as in 31 spline? if you go wth 31's than not only will you need a bunch of bearings and seals but a 31 spline diff too....if you dont want to spend all that money on a 31 spline set-up, I'd suggest atleast buying a rear diff girdle for your 8.8, it will help a 28 spline diff and axles last much longer....
2002 GT 5speed roush body kit with saleen s281 three piece rear wing totone black top red bottom fr500 nitto 555 275/35/18 with Eibach pro damper system BBK cai,BBK under drive pulleys,Headmen long tube headers,BBK off road X pipe,flowmaster 80 inlet and outlet same end so the roush side exit works,roush lower control arms roush sub frame connectors brenspeed x3 zex nos 125 shot hp257 tq295 on motor 380hp and 395tq on spray best 1/4 time now 12.770 at 115 with blowin the tires of in 2nd and 3d
its a cover with what i call jack bolts the press against the main caps to reduce flex. i believe thats right
you are correct and in addition, it's aluminum which helps dissapate heat better than the oem steel cover, thier usally a bit larger so it can hold more fluid and the better ones will have a fill & drain plug on the back....
upgrade to better axles? 
