and I can't seem to get the rear one unclogged. Does anyone have any tricks/suggestions???

I thought they just made a straight shot through the block and back to the pan..... I was wrong.

? huh?
Is the intake manifold on the car still?

Yeah, the intake was on the car. I finally was able to dig enough crap out of them to be able to blow them clear with compressed air. It was the holes at the upper front and rear of each cylinder head.