96 Grand am gt 3.1 L to3.8 L will it work

Have a 3.1L in my 96 gt will a 2002 3.8l work in it  

If it is anything like my 95 Grand Prix, the motors are virtually identical and the swap should be easily done, so long as you swap transmissions to.  

This is not a straight forward swap, the 3.1 is a 60 degree Chevy design V6 and the 3.8 is a 90 degree Buick design, no parts interchange between the two designs. There are likely motor mounts etc available to bolt it all in if you look for a similar platform/chassis from another GM car such as a Regal or Century from the same year. Then you have the hassle of making the electronics and fuel system work. It can be done but it's not a job for an amatuer or the corner garage (they would lose their shirt's on a job like this!) and when you are done, if you can get it to run right, you still have a car that may ar may not legaly pass an emission test. Then there is the resale issue, who wants to buy a car that is butchered together and you can't order parts for 'cause you don't know for sure what they fit.  Better option is to buy a 97-up GP and get the better motor to start with.  
A little help... 'cause we don't all have to learn the hard way!

I agree with Barney Formula all together, if it is not meant for the car, it is unlikely to be worth the trouble.  

Absolutely correct how much of a benefit versus difficulty of swap