I have a fresh c6 bolted up to my 351w. When I first started it I was able to drive about 1/16 of a mile. Then forward no longer worked. I can drive in reverse but nothing going forward. Fluid levels are fine. TC is engaged in the pump. Which issues/problems could cause the tranny not to engage the forward gears? The neutral safety switch wires are not attached, vacuum lines are a bit suspect, but could this cause the tranny not to engage forward gears at all?