Hi Malcolm,
There is a strong possibility the c/n is 5797.
I looked at all the UPF-7 photos on a.net and noted reg nos close to 32165 and their relevant c/n. (5 reg nos from 32133 to 32168). I entered all no's in that range into a spreadsheet, entered the first couple of c/n then used the auto fill for the rest of the range. All c/n shown on a.net matched the auto fill list for the available reg nos. It would appear a block of reg nos was reserved for the production run.
From this list the c/n for 32165 is 5797.
Unconventional method of searching, I know.