Swap in Corolla ECU and Transmission to '00 celica?

[imzjustplayin]

I have an idea for a Celica '00 where I'd swap in the transmission and ECU from a Corolla of an '01 or the like and the reason why I'd think they work is because they both have the same engine. So I was wondering if anybody had tried this or could explain to me why this swap would be more difficult than it currently sounds (to me)? Somebody said something about engine harnesses and whatnot being swapped but that doesn't seem to make that much sense to me since they're both the same engine.