if i was in your shoes i would rebuild what you already have ! the plus side of rebuilding yours you know what you have ! problem with that motor your talking about it has 69,000 miles which isn't alot, but still ! you really don't know how the motor was run, even being an explorer, if they changed oil regular . price seems little high to me, thats just my opinion ! i say rebuild yours . this just my 2 cents though !