i own a 95 grand am gt with the 3100. i was thinking about swapping it to like a 99 model 3400. is there a very big difference in these engines? they look the same, so are they? will the electronics work on the newer gt engine? would i be getting into more than i can handle? im a real good mechanic on older cars, but my knowledge of auto electrical systems is nil someone please help me out

The 2.8s, 3.1s, and 3.4s are pretty much the same engine with different bore and stroke. Now as far as is this a true plug and play swap I'm not certain if there are differences in any of the sensors, but I would imagine anything needed could be swapped over to the 3.4 since they're the same block.