Originally Posted by
murkeywaters
A lot of it is luck to be honest but there is always the gamble you have to weigh up, the older the Speedie is the more expensive the parts if you need to replace them with original parts.
I looked at a 105.012 pre moon with papers the other day for just under £5k, it sounded like a bargain but on inspection it had the wrong case back, wrong chrono hand, wrong pushers and needed a big service, actually it looked like an original 145.012 but the papers said 105.012 and purchased 1970 so a late date for this reference, I wasn't able to see the inside of the case back to verify either way, in this case you have to weigh up what its worth in parts to get back to original if the case back verified its a 105.012.
The case back, spear chrono hand and small pushers which would be needed to return to original are like hens teeth and your at the mercy of the seller.