2 part question. i have a 3.3 2005 grand caravan, with no tach. i found a speedo assembly with a tach out of a 2004 with a 3.3, i am pretty certain the tach will work, i just want to make sure. Also I am wondering if anybodys knows how much of this van is already prewired for upgrades. for example i originally had 4 speakers in the van, 2 in the front doors and 2 in the back. I looked under the top dash panel where there are speaker grills and there was speaker wiring ready to go. i notice the chain assembly for the auto sliding doors, do i only need a motor for it. If i wanted to install the overhead console that shows remain fuel, temp and so on. is that prewired? just curious.