Thun 1 piece cranks , now thats an old rarity from waay back. US made bike stuff attracted high import tax tarrifs in the early 1980's , so we never saw 3/4 of the US made stuff on the bike shop shelves for sale , only got to read about new products in magazines like BMXA or Action Now magazine....Apart from the way you pronounced the name was there anything special or differnt about them ?
We had the choice here bitd of either Takagi's or Flite cranks if you wanted strong cranks for your bike.
At $25 vs $275 new , the choice was kind of made for you as a fresh teenager who had just outgrown (broken) his alloy cranks.
The PUCH frame must have had a reasonable length to it , I built up a TJ Thruster & found it waaayy to small to comfortably ride around on , I stand 6ft bare feet.
The frames that came out of the Speed Unlimited workshop , no matter what the brand were always high quality stuff , I think the welders there had pride in all their their work , either welding up a drag/rocket car chasiss down to a "simple" double diamond BMX frame.

They probably did make a Thruster with the PUCH frame geometry , but it wasn't this TJ Thruster 17 1/2
in top tube length is just waay to confined for me to ride, the rear end measures up great , just too far too short in the front....it's just sitting as a frame now , I'm still wondering what to do with it.....
JB