why is my engine/trans rattling and why will it act like its in neutral on 2002 Subaru Impreza WRX

02 frame, 04 rear end and 06 front end swaped over to a STI

Asked by for the 2002 Subaru Impreza WRX
check tranny fluids for colour and level. bring to tranny shop for diagnostic. tranny tech. will advise.