Also see earlier post today in the "wanted" section.
On the left is a "TF10" (the last of 5?), at right another. I can't recall the name of the latter, can anyone refresh my memory? I have had them both for many years.
These engines are incredible when enough PSI is pumped into them, making a loud high-pitched screaming whine that sounds just like a big turbine, and then lasts for minutes as they wind down. Its all about the audio with these.
Too bad it requires dumping almost the entire contents of a 5 gallon air tank at 100 PSI all at once, but it is absolutely worth the trouble!