Thanks. I didn't buy the wallet because date code is nowhere to be found. Seller said she phone LV after realizing this error but according to her, SA said some item doesn't have it. I refused to believe thinking receipts can be faked and chose to walk away.You could try Yoogis website. Do a search for Louis Vuitton zippy and then choose "sold" (at the top on left). You'll be able to see all the zippy wallets they've sold with their year of production. They list the current sales price (usually meaning from that year).
That may help in your research.
I have heard of date codes not being in all SLGs though I've never experienced it personally. It could also be that she doesn't know where to look.