Engine How To Tell If I Have The Original Motor?

[Fordman2011]

I have a late 2001 mustang gt. When I bought the car it had a T-45 transmission already in it. I'm assuming that one of the previous owners blew up the 3650 and this is what they got from the junkyard. It got me curious if they may have blown up the motor as well. Is there a way to tell if I have the original motor?
The 8th digit of my Vin is an X. Does that mean it is supposed to have a Windsor motor? Because it definitely has a romeo in it.

 

[wmburns]

A 1999-2000 GT that originally came from the factory with a Windsor motor also has an "X" as the engine VIN code. The engine code really can't be used to tell the difference between Romeo and Windsor for the Mustang.

As far as Ford is concerned, at the VIN equipment level, there isn't a difference between the 99-00 Windsor and the 01+ Romeo.

And since Ford does not put VIN numbers on motors, that method is also gone.

A salvage motor will usually have codes written in paint on the crank. Most salvage yards put an over temperature "tells" on the cylinders heads. So if you happen to find it, that likely means a salvage yard motor has been installed.

Beyond that, I'm not sure how to know for certain if the motor has been replaced.

Why does it matter?

 

[Fordman2011]

A 1999-2000 GT that originally came from the factory with a Windsor motor also has an "X" as the engine VIN code. The engine code really can't be used to tell the difference between Romeo and Windsor for the Mustang.

As far as Ford is concerned, at the VIN equipment level, there isn't a difference between the 99-00 Windsor and the 01+ Romeo.

And since Ford does not put VIN numbers on motors, that method is also gone.

A salvage motor will usually have codes written in paint on the crank. Most salvage yards put an over temperature "tells" on the cylinders heads. So if you happen to find it, that likely means a salvage yard motor has been installed.

Beyond that, I'm not sure how to know for certain if the motor has been replaced.

Why does it matter?

The only reason it matters to me is that I have 175k miles on the car and if it still has the original motor, id like to keep it original and just build it next summer and if it is a replacement motor then id like to do a 4v swap next summer.

 

[Fordman2011]

Thanks for the valuable info! i looked at the date code of the car and it is 05/01 and the date of manufacture for the motor is 05/15/01 so it is highly likely that the motor is original to the car. The transmission code is in fact a K so I know that it has been replaced at some point in the past. Just incase anyone is curious, the reason why I was asking was because i have a thing about keeping the original block in a car and since I'm at 175k miles, ill be rebuilding her soon but if it was not original i would have just done a 32v swap into it and called it a day.

 

[bhuff30]

Any specific reason for the rebuild/replacement at 175k? With good maintenance, it should still be strong and tight and have plenty of life left. If you are planning a power adder build, it makes sense, but if it's just because the number seems big, don't worry about it. These engines go 3-400k in fleet service, with simple maintenance and maybe replacement of the timing chain guides/chains.
My GT is just a few hundred miles short of 220k and still runs very strong. In fact, my best time at the track came with around 200k. To be honest, the suspension hasn't held up as well. The ball joints, inner and out tie rods, and wheel bearings have all been replaced at least once.