I am going to replace a worn drive axle. Is the nut a 28 or 29mm? When the engine is cold, the transmission surges and is reluctant to shift forward. The ATF and filter have been replaced at 30K intervals. This helped the first couple of times for awhile, but the performance began to decline after a few thousand miles on new oil. At the 90K change, the surging came back even sooner. Any ideas?