Delighted to see this thread reactivate itself. It’s been fun reading the replies, even if they weren’t specific to my question.

Meanwhile, I think we figured out the answer: ‘Bloodline’ by Glenn Campbell. The line our listener remembered was actually ‘It was something of wonder, that steel-plated thunder’. Here are the full lyrics.

BLOODLINE (Glenn Campbell)

In the eyes of the old ones
Who watched from a distance
It was a devilish magic at best
But the hearts of the children
Were filled with excitement
As they dreamed of their house in the West
Oh the engine would fire the black smoke would rise
Thru the spray of the slick silver steam
It was something of wonder that steel plated thunder
That moved the American dream
That moved the American dream
I can hear the sleepy whistle blowin'
I can see the spark beneath the wheels
As the leaves the hills behind her
For the ragged cotton fields
In a dusty one-house station
All the children grow impatient
As they stare into the distance for a sign
Here she comes can't you hear her whistle whine
Here she comes rollin' in my bloodline
Running' in my bloodline
Old man Grady waves his lantern
"All on board" I hear him cry
While Lucius stokes the cinder
And wipes the coal dust from his eyes
Yes she was prowd and full of fire
As she road that silver wire
>From the Kansas Plains to the great Sierra Pine
Here she comes can't you hear the whistle whine
Here she comes rollin' in right on time
I can feel her she's runnin' in my bloodline
Runnin' in my bloodline
Here she comes
Now the stockyards are empty
The steel rails are rusted
They belong to the wind and the sand
But we long will remember
The steel and the timber
And the pulse that once beat thru this land
Oh the engine would fire the black smoke would rise
Thru the spray of the slick silver steam
It was something of wonder that steel plated thunder
That moved the American dream
That moved the American dream
The American dream
Dream ...

Thanks for being out there, Mudcatters. Carry on!