There is a conflict with Chrysler and Tremec (MFG of the SRT10 manual 6spd) on what type fluid to use in the manual trans. The truck's manual says to use only gear oil...even has a warning stamped on the pan of the trans that warranty will be voided if anything other than gear oil is used. Tremec's service manual ( http://www.ttcautomotive.com/English/media/pdfs_autogen/T-56_Service_Manual.pdf ) says to use Dexron III ATF. This is a poll to see what owners on this forum use. If you have never serviced the trans or has been serviced but you do not know what fluid was used then click on "Mopar Gear oil". ..