well.. I just went to Advance Auto parts.. and guy at the counter. said you know where the gas caps are in the back.. just go match one..  and I found one..  later bc

Really? Use Google translate or just call them. And things can be mailed from Japan. It's not that difficult. 

Depends on spi or carbed i believe.
As long as the tank is vented i like dsgruntld buy the non vented one.

I bought this one.
The injected cars use a nonvented cap to make sure the pump works properly.

Well, I had googled but didn’t see that one, but probably because it is in Japanese.  Anyway it looks like it will be tough to replace that key.  When I look at non-locking caps, I see vented and non vented versions.  Which one should I get?

Locking gas caps on US Minis have always been considered a Liability in my book. Too easy to lose the keys and no easy way to reproduce them. I have always taken the locking caps off of any Mini I have bought and threw it away! FWIW, if you ever do find yourself with a locked cap and no key, I have a large pair of channel locks that we normally use for oil filters that you can grip the cap and twist until it gives up. Yeah, you may end up pulling the tank to retrieve some of the broken cap, but sometimes they do come off in one piece.

I just replace most of mine with a non locking gas cap.

Try.. www.ebay.co.uk   and punch in year..  yea  I know the shipping is more than the Key. but life is NOT fair.. later b

I just ordered an all new gas cap (which comes with 2 new keys) as the lock was a little tired on my '95.

Should I assume you tried googling those numbers? This is one of the results I found.

https://page.auctions.yahoo.co.jp/jp/auction/337396083

I was able to get my ignition and door keys copied by a local locksmith, but he could not find a blank for the gas cap key.   This is for a 1992 rover mini.  Does anybody know where I can get a blank?  The number that is written on the key is k236.  There is also GSS