G'day all,  I have been searching the net for info on the Newcastle LR & have seen that 2151 was the number on the tram even when it was an artist's impression back in 2016. Interesting.
As for the origin of 2151, they should have kept that for Nth Parramatta as that's its postcode. But I digress !
I thought for a minute it might be a continuation of the last number on Newc trams, but soon remembered that only LPs ran in Newc and they were only in the 200 series ???   so the 4 digit series was never reached.
As for 003, 001 & 002. it seems silly not to add their number when the tram is finished. But why paint a number like 003 anyway. couldn't they just have a cardboard sign on the dash ? eg: 003 / 2127. 
Anyway, enough grumbling.
Bye for now.
Tim, in Sydney.