i need to replace my o2 sensor but i dunno if its the origanal one or not

because the owner before me replaced the engine with a 350
but i dont know what year it is

but i was curious if the o2 sensor would be the origanal or not

 

What are you asking? Are you asking if the o2 sensor is the original as in has it been replaced? (how should we know?)

Or are you asking whether or not the o2 sensor is engine specific like pistons? In which case, no, the o2 isn't.

 

yea im asking if i got the o2 sensor fo rthat car would be same as if it was on a 305
would it matter?

 

AFAIK, the sensor is the same for the 305 and the 350.