Your Grand Prix used GM's "W-Body" platform. A number of other GM vehicles used that same platform over the years. Wikipedia had a nice listing of all of them so I included it in the sources below. Any of those models listed should be able to accept your 3800 and transmission without a lot of trouble.

I'm not sure how much of a project you're looking to take on, but one other car that will house a 3800 V6 is a Pontiac Fiero. Your 3800 V6 in a 2500 lb. Fiero would make for a surprisingly quick little car for not a lot of money if you can find a non-running Fiero somewhere anyway.

There are junkyards in the Chicago area. Victory Auto Wreckers comes to mind.

Make one with glass fibre. Or if you're good with metal work buy some steel sheet make some woodern formers from which you can shape the steel body pannels on by beating them to shape, then mig weld together.

junkyard

I have a 3800 V6 that came out of my 1998 Pontiac Grand Prix. Were can I get another car without the motor and transmission. I tried Chicago Craigslist and got nothing. I have $400- $500. Can my motor and trans fit in a different car ?