you just got into a twist-o-plex of numbers and info
not to worry though your not the onliest one.
Just did this myself.
the Aisin 340 should be good to go provided engine/veh model are fairly close.
Check your tranny wiring up in the engine bay to see if the plugs match up to your donor tranny..
if they don't it can be modified but I was advised against it due to the fact that if the plugs are different then modified the ECT maybe different in in say a gen I to genII 4runner..
inshort if the bell housing and plugs match you should be able to to do it..
Keep in mind like Auto makers,Aisin makes minor mods to their gear through out the model years thus the number/matchup game.. bottom line is "A340 is A340" Yuji Nishioka 2004 Japanese mech helping me with my tranny
check this thread out on Wildyoats
catagory: trucks and 4runners
Thread: Auto tranny
there maybe some helpful info there
BTW thats my handle at wild yoats