Ok ...
So I found this information on another forum. It answers my question
Thanks to "Ben,from Australia", a collector of Lithgow-made Slazenger rifles.
"The full production list was:
Model 1 .22LR single shot
Model 1A .22LR single shot
Model 1B .22LR single shot
Model 12 .22LR bolt action repeater
Model 55 .22LR bolt action repeater
Model 24 .22 Hornet bolt action repeater
Single Barrel Shotgun .410 single shot bolt action
"Slazenger" and "Lithgow" are used interchangeably to describe their manufacture, both officially and in common use today. Technically, they were made by the then-government owned Lithgow Small Arms Factory in Lithgow, NSW, using wood furniture produced by Slazenger, and sold under the Slazenger sporting goods brand.
Both Model 1 and 12/55 rifles share a fair bit of DNA from Winchester rifles of the 30s and 40s - I believe the Model 67 and 69 rifles respectively. Famed Australian demonstration shooter Lionel Bibby, Slazenger's main designer, had previously worked with Winchester.
Differences between the Model 1, 1A and 1B are minor. The Model 1 used a trigger design held within the stock, whereas the 1A/B used a trigger design fixed to the action as per contemporary rifles. Early Model 1s used a screw-in rear sight, latter going to a dovetailed design which was carried over onto the 1A and 1B. Early Model 1s supposedly used a one-piece coachwood stock however every Model 1 I've seen has used a multi-piece stock. Other differences are purely cosmetic... the Model 1 used a white-on-black "kangaroo" emblem on the right hand side of the stock... latter versions had a smaller, embossed black logo. The typeface on the LHS barrel markings changes across models too. Early Model 1s don't mention Slazenger, just Lithgow Small Arms Factory.
The Model 1s were the basic, affordable rifles of the era - light and easy to handle - and often the first rifle a young boy (or girl) would be given. Standard sights are very basic but they are very accurate and more than capable of taking down rabbits, birds, rodents and wallaby. With over 220,000 produced they are very common today and most gun stores will have several available for less than AU$50. Unfortunately due to our convoluted permit-to-acquire process and limits on junior shooters, they tend not to be big sellers and many have been handed into police for destruction, which is sad. People are slowly catching onto them as something worthy of collecting, though." So based on Ben's information I'm leaning towards getting a Model 1A or 1B because it sounds like there was a significant improvement with the trigger mechanism as compared to the Model 1 and a minor improvement in the way the sight were fixed to the rifles.
Other than that,so far it appears that the differences are purely cosmetic.
Other noteworthy facts are that the barrelled actions were made from surplus 45t proved .303 blanks, which is steel of much higher quality and strength than required for a .22LR
Stock timber was apparently the same timber earmarked for No. 1 Mk III* production.
Iv Also found some very good information here
https://www.lithgowsafmuseum.org.au/comproduction.htmlMore info was stolen from here
viewtopic.php?f=17&t=3539I've tracked down 2 rifles, both Model 1A, I'll be inspecting them very soon