#1 and #2 mean the same, and they are not ambiguous: rebuilding happens after original manufacture, usually to enhance its power or design by customization. #1 emphasizes its present existence; #2 focuses on the rebuilding that took place. I prefer #1 (if either were ambiguous, it would be #2-- the speaker could be pointing at a heap of wreckage as s/he speaks).
#3 is correct; #4 is not: the dependent clause is not a question, so do not invert subject and verb.
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