dunno about the gasket...pero sa Banawe merong Ford/Mazda specialized parts shop dun....naka-limutan ko lang pangalan....
yung tungkol naman sa ATF, what do u mean parts? AFAIK, no other user serviceable parts in A/T.
pero take note though that some Car makes have ATF compatibility something.... in other words. some cars A/T would get damaged if totally changed the ATF. others are no problem... sounds weird right? but i got this from a Japanese car-buff. i'm not sure about the Mazda MPV's ATF, but to be sure.... try mo muna to drain just half. then top-up. then 3months later or so repeat the procedure. drain-half, top-up .
also take note of ATF level during hot and cold tranny and engine running or engine-off is different. to be sure pls. refer to your Mazda manual for these....