Hi Tomo,
Would not bother with the heritage certificate I will tell you exactly what I have told you as they get the information from the same books. I have access to information from Gaydon that was recorded in the late 1990s.
Technical Specification Package won't tell you anything more then what you don't already know. Best have a look in the front of a TP/138/A Workshop manual as these suite 1950 Models best. This gives a tech spec.
A few Test run CKD's were done by Regent Motors in 1949 and pretty much that year was spent getting ready for them. They started to arrive in Bulk late 1949 for the 1950 Model year. Regent Motors got a few in the 06101300s then Grenville's Sydney, Then finally Annand and Thompson got them around vehicles 06101680ish.
Gearbox is out of a vehicle that was outside for a very long time and would need to be totally rebuilt. You can have the box I don't need it I would rather see it in a vehicle that is going to be restored / rebuilt.
If you have a look on the engine mount passenger side it should have a build number. Also if you can find your axle numbers this will give us a good idea what the orgional gearbox and engines were numbers wise.
The engine would have been a 1600cc Core Plug engine with a square sump and the earlier type oil pump.

