Need Help ....

I know that you can drop in a 3800 V6 in it but can i still leave the manual trans that it already came with..???? or do i have to switch to an automatic that the 3800 would come with...????
please help... :banghead: :banghead: :banghead: :banghead: :banghead: :banghead: :banghead: :banghead: :banghead: :smokin: