kiakiller

i just bought an 05 v6 auto last week, i drove 3 hours to get there and 3 to get back because i was sure i found a good deal maybe too good i paid 13 for it all options avail for 05 w/29k on it. but even hitting small bumps in the road there is very loud thumping for the rear. i checked the spare it is down tight but i am starting to think it might have more problems, is there anyone here that has unlimited carfax and can hook me up, just wanted to check before i pay 30 bucks for it to prob tell me i bought a jacked up car. the vin is 1ZVFT80N755252024 thanks alot i appreciate it and also if anyone has any idea what the noise could be please help me out