I have an engine block that is giving me trouble identifying. I was told it might be a cadillac engine. It has a stamped plate that reads *6DE825441 and a cast that reads X1618864. Any help would be appreciated.

pics to follow

pics

if there's somewhere specific to look, let me know

That is not a Cadillac. I think it is a Ford FE! Anyone else venture a guess.

On the shiny plate, it reads GM all over it in the background.

From the looks of the block, it looks aluminum, while the heads (which have oxidation) look to be cast iron, which leads me to believe that this is a 4.1 4.5 4.9 series engine. The shape of the heads also seem to look like the 4.1 heads that were in my 85 FWB. The shiny plate (with GM all over it) seems to be something that would be on more recent engines than the big block Caddy engines that this forum discusses. You may want to post this in the 4.1, 4.5 ,4.9 forum. Before you do, see if there are any numbers actually cast into the block like 4.1 or 4.5 or 4.9 GM used to cast the displacement in litres on the block on engines made in the 1980's ( I have seen this in other GM engines). You may want to get pictures of the top of the block where the transmission is cut off as well as the valve train when you post this in the other section.

Bingo, you got it. I am looking at my Allante FSM and it is a 4.X.
Measure the bore and stroke to find out.
The 4.5 has 3.62 bore and a 3.31 stroke. the 4.1 has the same stroke as a 4.5 but smaller bore. The 4.9 is a stroked 4.5.

According to the FSM the engine ID plate is at the LH side rear on the block but no mention as to what the number means.