Just bought an 03 Monte Carlo. It has a 3.4(3100) Car itself is in great condition. Still runs great. Tranny slips a little bit so, Im looking to upgrade a little sooner than I thought. i have found a (3500)complete with tranny.
Im wondering how easy it would be to swap these out. What all would I have to do,

 

I believe you have a small piece of info wrong, you stated "3.4(3100)", I believe you typo-ed, as it should be a 3400.

To my knowledge, the 3500 can be direct swapped into any car that had a 3100 or 3400 (as it's the same block) from a mechanical/fitment perspective. You will have to make some changes, such as the 3500 was drive-by-wire and you will need to adapt a throttle body that uses a linkage cable. You will also have to switch the ignition system over to use the coil packs and ICM you have on your 3400. There may be some other small things here and there (such as injectors, sensors and wiring), it will definitely require PCM tuning adjustments.

As for the transmission, no clue. You first need to know what transmission you are getting (just like the 3100/3400/3800, you can bolt up different transmissions to them and the factory did just that depending on what car the engine went into). Do you know what model transmission you have access to?

I know some Grand Am guys have a bit more knowledge on this topic (as this is more common in the smaller platform). I believe Milzy Motorsports is a vendor who may be able to provide some information and possible parts required for the swap.

 

Thanks! Sorry, about the long reply. Yes, it was a typo.
I didnt get the motor anyways. Cause it did not come with a computer.
However I have tracked down a mostly intacted 03 SS.
I'm going to pull the motor and overhaul it, for a supercharger. Or turbo, haven't really decided.
What are things I would have to upgrade.
Pistons, cam, maybe crank?