Under the agreement for cancelling the last 3  locomotives and accepting 3 complete but  in parts and another 2 as incomplete locomotives was the provision that only 42 locomotives would ever operate at one time. That is, NSWGR were prevented from building another 3, 6043,6044 and 6045 as they did with the 81 class. The boiler units of the 3 complete locomotives, 43, 44 and 45 were used and I think I have seen a photograph of the builders plate from one of these on a locomotive.
I don't know why BP were so difficult over this, their order books were full at the time and they went on to build another 300 locomotives themselves and subcontracted a large number to other builders because their shops were at capacity. The SAR GMA/M class followed on from the NSWGR 60s, followed by the RR 16A and 20th classes, some for Angola, and finally the EAR 59 class.
I scored 95%, not knowing where 3214 ended up.
A very enjoyable quiz.

If this is true, why did Beyer Peacock issue builder's numbers for locomotives up to 6047 (and not 6048-6050)?

It seems that the NSW Government were the ones concerned with limiting the number of locomotives in traffic.
I can't see how Beyer Peacock could enforce an agreement not to use locomotives delivered complete...
(Refuse to supply the 46 class still on order?)

I recall seeing a Garratt at Enfield which had a steel oval plate in place of the usual Beyer Peacock builder's plate.
It had a four digit number starting with "7" welded on it.
In those days as a poor student I couldn't afford to take a photo of something just because I didn't understand it.
But my memory suggests that the number was the builder's number of a locomotive numbered above 6042.

Since the cab numbers were often changed at overhauls, the builder's numbers might have been a convenient way to track which boiler was where, and this might have extended to locomotives that didn't actually carry plates.

Weren't the SAR GO class among the last built?

I had looked up preserved locomotives on line a few days before doing the quiz, so knew where 3214 was...

Peter

The only reason I could see for it is that there were in reality few spare boilers for them, those assigned to 43-50, meaning only 8, although perhaps additional ones could have been sourced from 6003, Geurie crash, 6012 first withdrawal & 6020 following collision at Mascot, making 3 extra's available.

IIRC, Cardiff was the primary shops to provide for CL1 heavy overhauls, along with CLass 2 Medium along with Eveleigh which carried out the Class 3 overhauls, Class I's usually involved the boiler unit being removed from the cradle although sometimes that happened with Class 2's. The class 1's involved the removal of the top section of the cab roof for ease of lifting and replacement.

The one thing that was always part of the mentality though was the need for speed and getting them back into service outside of drought times when they were in big demand, naturally that incurred some swifty type movements whereas the head of the branches turned a blind eye to, up to a point.  On other occasions there were some strange changes made as there was with 6015, it was modified to heavy type early in the 60's, and was then reverted to light type some time later, for use on the West and allocated to Dubbo/Parkes area working for the 64/65 wheat seasons, IIRC the allocation took place in 63, when the garratt's were pulled out of the west, it was converted back to Heavy type and spent its remaining years at BMD.

I still wonder with it in regards to the Cylinders when it was in the light configuration during that intermediate period.

Of the other light types, 6038 was a late withdrawal as it was allocated to BMD for a while and used on Muswellbrook coal working, turning via the triangle at MBK to run engine first both directions.  Its final journey was to Enfield for scrapping and worked a full load from BMD yard one afternoon, the date I have somewhere as I was the fireman on it. Driver was the late Barney Hough. We were assisted from the river by a 46cl, and a certain well known enthusiast engineman there had a tape recorder set up in the back cab to record the event, (would love to have a copy of that), once we were part way up the bank, 38 showed the old habits of light types as the water in the front tank dropped down, it started the slipping, Barney handled it well, and with the slow slog up the bank, I experienced the stories of cab heat in the tunnels there, likewise through Woy Woy.

IIRC I was stumped by the Harbour Bridge crossing and forget the other one, but I instantly knew I chose the wrong option as I clicked on it too quick, happy with 90% though.