It's a Pratt & Whitney JT9D-7A/7F/7J, not a JT9D-7R4D, and was not used on Boeing 767s. 7R4Ds were used on Boeing 747s, not Boeing 767s, and the Church & Murray was an "A"-line older version. it's either an 7A, 7F or 7J.
A key difference between 7A/7F/7J and the 7R4D is that the older (the kind found at Church & Murray) had a Stage 1 Cooling Duct Assembly (with those little "elbow" exhausts), which was replaced by a later version in the 7R4D.
Another clue that this engine did not come from Flight 175 is that
it shows no fresh damage or markings indicating that it had impacted with anything hard, which would have created gouges in the steel. Dusty, but no fresh damage.
Had something that massive hit at high velocity, it would have been partially buried in the sidewalk. But instead it's sitting upright, which is improbable by itself on the official trajectory. And the sidewalk appears to be undamaged.
Significantly, as I previously observed, Jack White discovered FOX NEWS footage showing agents wearing FBI vests unloading something heavy from a white van. In fact, they even left behind THE DOLLY that was used to unload it.
A photo with these elements in a collage can be found on many of my articles about this, including "Planes/No Planes and 'Video Fakery'". The fallacy DGM commits is known as special pleading, by citing only the evidence favorable to your side and ignoring the rest.
For those who want to follow up. see
http://www.veteranstoday.com/2012/02/20/911-planesno-planes-and-video-fakery/ When I figure out how to post images here, I will have a lot more to say. In the meanwhile, it would not have been necessary to plant parts if there had been an actual crash.