I bought my 8 with 46000 miles on it from a guy that knew nothing about it supposevily... i was just wondering how i could figure out if its had a new engine put in or clutch, tranny, etc? could i just call mazda and give them my vin number?

yes let them run the vin# and they will tell u what re-calls have been done and what mazda did to the car as far as fixing other problems..