Welcome to the all new Holden Heaven
 Number 1

Number 1
This is an account of the first Holden that was ever made which doesn't include the Holdens in the early part of the 20th century that Holden built on the GMC chassis!  You can read about that in the GM-H History page.  The 1st Holden identification plate reads 'General Motors Corporation', not GM-H. This car was first registered in America in September 1946 as BK46-48 and was built in Detroit. It's original Australian registration plate was JP-480 and was registered in Victoria on 12 February in 1947 as a blue Chevrolet sedan with engine number 1946/2. It arrived in Sydney from America late in January and under the cover of darkness with its 2 sister cars was driven to Melbourne. This is probably a strange thing to do for a brand new never been seen before Australian car but I suppose it was a great way to run the engines in and give them a good test from day one.
There were few photographs of JP 480 as it was used as a test car for most of its early life and the glamour work was done by the second Australian built Holden KY442.
Although this shot shows JP-480 lapping up some of the glamour it deserved!
 SP-480 (Number 1)
It was JP480's job to be tested for durability, economy and braking which meant it was used and abused in ways that no normal person would treat there new car.  The other two cars registrations were JP-481 and JP-482, these two were used for durability testing in the Dandenong ranges which the conditions were best described as tough and grueling. What better way could you find out if this new car could cope with harsh Australian conditions. 
Specs for Number1: 
Style No: 19525 
Body No: 1 
Trim No: 101 
Paint No: 1 
Serial No: n/a 
Engine No: 1946/2 
Replacement engine No: 59244 
American Rego No: BK46 48 
1st Australian Rego: JP 480 
2nd Australian Rego: ZW 234 
Original colour: Blue 
 The Holden badge was a late decision
 After JP480 had done 24,000 km of testing the engine was removed and stripped and is maybe still lying around in someones garage because it was replaced with No. 59244 which as far as I know is still in it! Also no-one knows what happened to the original engine and by the sound of it the possibility of it being dumped was high.  So the next time you see a grey motor at the market or at a garage sale who knows you might be the luckiest Holden owner in the world. So after a while it's registration lapsed and it was re-registered as ZW-234.
All three cars were registered as Chevrolets as the Holden name was never settled on until just before the launch and the name on the bonnet was GMH not Holden like in the final production models.
The Others
This shows the most photographed of all the prototypes KY442 which was the second of the Australian built cars.  This car went to all the shows and special launches that it possible to go to.
Just to keep the record straight the details of the other two are as follows.
Number 2: 
Body No: 2 
Serial No: n/a 
Engine No: 1946/3 
Rego No: JP 481 
Colour: Green & Black 

Number 3:
Body No: 3 
Serial No: n/a 
Engine No: 1946/4 
Rego No: JP 482 
Colour: Black

The Engine
The engine was derived from a prototype Chevrolet which Hartnett was told about in 1944, code numbered 195-Y-15.  This engine had been gathering dust in the General Motors Detroit design centre and was so close in specifications to what was wanted. 
By using this engine it would also shave off about 2 years and countless dollars, so the decision was made to modify this engine for Australian conditions.

Holden 4-cylinder!
I wonder if anyone realises just how close the first Holden had come to being a four cylinder instead of the original six? Bill Knudson (president of Chevrolet) and Lawrence Hartnett had a bit of a wager about which engine configuration could be made cheaper! Specifications were drawn up using the same low-cost car with identical basic performance, torque and horsepower. Bill Knudson and the six cylinder won the argument because it needed less beefing-up of the gearbox, clutch and back axle and therefore was ultimately cheaper to produce! 
Thank goodness for that!