s13 engine into s14 body please help

[EckOMaN2k]

Ok well im suppost to be buying a guys s13 5spd transmission and his engine its from a 91 240sx. And im swapping his transmission into my car and my car is a 95 240sx automatic. Now i will have all the manuel parts i need to the transmission swap. But i heard that the s13 motor wont just slip right in i mean they are the same motor right, also ill have the s13 ecu and harness too. I dont possibly see what problems i will run into with swapping the s13 engine into my s14.

So if you guys know anything or possible things ill run into please let me know because im going to pick up the guys motor tommorow evening. so if any of you can respond by tonite id really appreciate it. Or IM me at eckoman2k or Rcr2k2 if you have anything to tell me.

Also the guy has a 96 or 97 240sx transmission and engine for sale with 5spd i could get so let me know about that too.