US-Specs -vs- Japan-Specs ECU.
 

I will like to know if there is really any diference between the J-spec ECU and the US-spec ECU. If there is, which are?
Can a J-spec ECU fit an US-spec car('89-91), without any modifiction (just plug it in). :)
Those someone imports ECU from japan? If yes, which is the address, how much is for those?
How can I identify a J-spec ECU, is there some serial number or code on them, that identify them as J-SPEC OR US-SPEC.

NOTE: DON'T consider the emision test. I know that the emision are different.