My transmission guy told me that many stock set ups are off from the factory. The tolerances between the block, crank, flex plate, torque converter, pump, and transmission case all add up. He showed me a pump gear and torque converter from a stock trans that he was rebuilding and you could see the wear on both parts because the converter was only engaged 1/4". He checks the clearance on all transmissions that he installs and he gives instructions and machined washers to the customers that do their own installations.
