intake help!!!

So I've got b2600i with a blown head gasket and in order to get the head off, you have to get the intake manifold off. If this truck was carburated it'd be easy, but it's not. The top nuts are easy to get off, but there's 5 on the bottom that are impossible to get to even with extensions. Any tips are appreciated, thanks.

Can you "feel" the bolt heads or nuts with your fingers? Do you need to use a deep socket if someone installed studs and nuts instead on OE bolts?

I was able to get one easy to reach one out and it was a bolt, and I'm able to feel a couple others but can't quite get to them.