I've got a 96 avp 3.4, bad motor, I can get a 92 3.8 can I swap the 3.4 for the 3.8?

Practically speaking, no. Sorry.
WHile the hardware - and that might include more parts that you would bargain for - might physically get in, all the surrounding electronics AND wiring would be incompatible....
3.4 commonly blow head gaskets and an overhaul for that is around 1200$ and you are back on the road, better than new.
.. sometimes they break the camshaft.....and that needs more attention....