Hi Jim,
The easiest thing to see, is the small exhaust manifolds. If you look at the exhaust manifolds from your first 2.8 V6 and compare them to this engine´s, you can see that the 2.8 manifold is much heavier and not as curved on the passenger side manifold of the engine. Look real close at that manifold and you will see that the rear part of the manifold, which is the one that covers the siamesed ports, is small enough to just cover one port. The front part of the manifold also has a small part that also covers one port. You will also notice that this engine has just two bolts on each port, holding the manifold on. The 2.8 has three bolts around each part of the manifold that covers each part of the head where the ports come out. The 2.8 uses just four bolts total and the 2.8 has six bolts total. Another thing you can see in this picture, is that the engine mounts are almost in the middle of the engine block, where your 2.8 has the mounts up front, under the fuel pump. Just one of the reasons my kit won´t work.
If it didn´t have the transmission on it, you could still see what it was. Since I have owned both kinds of engines, it is easy for me to see the differences. I wouldn´t expect you to be able to tell the difference, so if you want, you can ask me any time you need someone to identify one for you.
Jose