Motor Question

I have a 1998 Malibu that recently the oil pump went out and then come to find that I also bent a push rod and 2 lifters are gone. Not to mention that the cam is in half and I cannot seem to understand why because the car was running just fine except for the norm I had already posted that everyone seems to have issues with and already fixed most all of that. My question is when we took the motor out to clean it up and replace the parts we found that I cannot do that because there is a crack in the motor. But I have a 3100 V6 3.1 and on the side of the motor it is stamped made in Mexico and the 3100 that we are putting in it is stamped Made in the USA. Would there be a reason for this or has someone already been in my motor before? Thank you so much for your help in the past. And thank you in advance for helping me out once again! :crying: :banghead: