Hello David - not sure that this will help much, but some information from Vigier & Pina - 'Smoke and Ice'.........
According to the book, production Nos. consist of 3 to 5 digits, the last one being separated by a 'slash' , sometimes. So I'd suggest your figure 2 simply forms part of the production No. which in full reads 3637/2 - and the 2 doesn't have any other particular significance.
Again, looking at the book, regret I can't see any pre 1970 designer for whom there was a code of PA. Are you sure this is in fact what the letters are? I get the impression it's not too difficult to mis-read some of these hand scratched details.
Can say that this factory used the letter code A for cut glass - and this looks to be cut - but not sure from the screen. If it is cut, then the A might refer to that fact, leaving just the P to resolve, and the only pre 1970 designer for they used the letter P, seems to have been Palmquist, who was with the factory until 1971, apparently.
I might just have this all wrong, but am sure there are people here who are good at Scandi, and hopefully will have the answer for you