I got my heater put back in today, Kind of tough but not too bad if you take the front seat out on passenger side. Thank all of you who gave me advice on how to do it in the past. I found the reason for the steel pipes, the heater core has 3/4 inch hoses, the water pump and the thermostat have 1/2 inch, so the bottom pipe is 1/2 on one side and 3/4 on the other.  The top pipe is 1/2 on both sides so I used a reducer.

I have to say, I took the Pinto for a drive today after being away from it for a while due to the bad heater, fun,fun,fun. A guy in a new Mustang was ogling my ugly 2 tone blue/primer Pinto. I have the system full of water, I am going to drain it out when it cools and put Anti_freeze back in. The anti/freeze water has turned rusty looking each time I put new Antifreeze in. 3 times now.