There were several 60° 3.5 liter V-6's made by GM, some of which were used in the Impala. You might be able to use one of them. But the simplest solution would be to get the correct 3.9.I have a 08 impala that had a 3.9 engine that recently blew. Swapped it for a different one that turned out to be a 3.5 (seller told me it was a 3.9?) will i be able to use? Or should i just scrape it?
When you say swapped, do you mean you've installed the 3.5? Or just taken possession?
Are there any markings on it - numbers - which might help us determine which 3.5 variant it is?
Also, there's a sticker in the trunk, usually on the passenger side shock tower, that lists all the options included in the car. On that sticker will be a code for which version of the 3.9L engine the car came with. It should be either LZ9, LZ8, LGD or LZG.