The loss in power transmission efficiency is rated at approximately 16% in 4th gear for a 2005–2010 Ford Mustang GT.
TR-3650 used in the 2001-2004 Ford Mustang GT Note that in the other TR-3650 applications, the 5th gear ratio is also available with 0.68(05-10 with 3.55:1 final drive)[1] and 0.74.
In 2002 Ford Australia's vehicle were fitted with the following ratios: TREMEC engineers have recommended Texaco-Havoline Dexron III/Mercon Non-Synthetic ATF.
There has been a significant amount of confusion regarding the proper capacity and proper type of ATF for the TR-3650 which may have a correlation with a rather large number of complaints about notchy shifting, shift "nibbling", noisy synchros, and grinding gears.
Note that Tremec engineers have also recommended GM Synchromesh as the transmission fluid.