Ford Repair: 1997 ford pick up with repalcement motor, blown head gasket, vacuum ports

Question
Dear Steve,
Please resond to  this question from my husband.  He has MS and cannot find where he put the email or answer when he asked this question in the past.  
Recently I bought a used 97 f150 with a blown motor(it was seized up)anyway I bought a used 98 running engine. I replaced the motor & got everything hooked up right, but it won't fire. I was told that the cat. converter could be plugged. After I try to start it I have antifreeze coming out of the tailpipeI was in the process of changing plugs.#6cylinder has antifreeze come out. How can I tell where it's coming from? gasket? The only thing I changed on the 98 engine was the upper plenum because of less vacuum ports. Thanks Fred

That is why the question was asked twice.  I realize you have little spare time but he is beyond frustration at this point.  I have checked with Mitchel On line and could not find anything either. Thank you for understanding
Dot


Answer
Doris-

  I'd imagine that your husband's truck has a blown head gasket.  There are few ways that coolant can enter the motor, and the intake isn't one of them.  For starters I'd do a compression test on the motor (particularly the cylinder where he found the coolant).  I'm willing to bet it comes back low.  It's pretty hard to find out where an engine is leaking internally without pulling the head off...and by that time you should replace the gasket anyway.  Hope this helps.

Steve