if the 1996 has the stock intake then it will be all plastic. the newer ones have an aluminium crossover up front.

 

Not necessarily. The first years of the PI mustangs didn't have the aluminum crossover. I think the aluminum crossover started in 2002 but I'm not sure

Here is a good comparison between a PI and NPI intake. The PI intake is much taller and has slightly bigger runners. In both pictures, PI is on the left with NPI on right.
front view:

top view:

 

if you guys will notice - the first runner goes to the driver side on the pi intake, and the passenger side on the npi intake.

 

Yea thats a good way too tell..good eyes

 

Well, I found why he had an extra motor, while trying to get it started the motor was locked up. I tried to bar the engine over with breaker bar, tore it down to look into the intake and this is what I found, well I was going to post a picture but it got errored. I found about an inch and half of antifreeze. hsnap
What could cause this, I am going to fix up this Mustang but i don't want this to happen again. Is this a problem with this motor or did my brother not store it correctly.
One thing I did notice was the motor in the car, the coolant line that comes out the back of the water pump goes straight to the back of the motor. The one on the engine stand has a metal tube that goes out the back and then turns up and to the drivers side, and then to the back, Does this mean something, I am just trying to put this puzzle back together, to finish what my brother started.:banghead

 

the water pump line that goes towards the driver side of the block is a PI piece. it goes over too make room for the bigger PI intake manifold

 

Thank you for all the info, it has a PI intake, with new pistons, rods and windage tray.
but I still don't know how the antifreeze got in the intake.

 

On the plastic pi intake, the coolant port tends to crack in between one of the other intake ports next to it. Check to see if any cracks might be around the coolant ports that leads to the intake's. An aluminum crossover pi intake will be best for the future, you won't have that problem.