Thanks to both of you for your suggestions! We ended up putting both of the '04's ECM and TCM in (with the '02 engine and transmission) and somehow now the car is running smoothly. We needed to redirect one wire to get the radiator fan running. Otherwise so far so good, car is running and sifting ge...

Hi there, we are new to Volvos, and are new members here. We've done several other engine/tranny swaps in the past on non-Volvos without significant issues. We were given a 2002 V70 XC with a good body but bad engine and transmission, and a 2004 XC 70 with a bad body but good engine and transmission...