Double Chain Timing Case?

Image Attached. The engine is also a DOHC QUAD 4 engine, yet the timing chain is all about a double row chain and double row sprockets, needless to say.

Extremely needed and useful content dear Ken L (And you had been supporting my presence here 2 years ago with that irksome PCM issue, if you still recall it). Here, I have to clarify some point: The engine used on my 1995 Pontiac is bought from a local firm that imports used engines from all around the world and sells them as (fit to replace the original engine of Pontiac Transport & Grand Am models). The engine itself is already the same as the typical engine used on this car: i.E, a DOHC QUAD4 engine with a metal induction manifold, but the following differences distinguish it from the old one used on this car due to having a double-row timing chain, one that is exactly the same as that of Mercedes engines' timing gear:

1. The Timing Case is "higher", meaning: it gets closer to the right-hand upper engine mount. This is to allow for the double row sprockets of the camshafts as well as those of the water-pump and the crankshaft).
2. It has a provision for lubricant vent /Pressure relief of the timing case in the form of an opening within the aluminum case itself (facing front) whereas the typical old timing case has this vent line as a metal tube within the steel cover of the timing case. The metal tube is attached to the black plastic box on top of the induction manifold through a rubber hose.
3. The geometry of the timing case edges differ from the typical timing case housing a single-row chain and sprockets. The steel cover is not interchangeable here and there.
So, what happened to my engine? The mechanic caused the timing case to endure a fracture right where the tensioner is attached. He welded and machined the weld location and then mounted the whole thing again. The engine is running fine, but there is a lot of lubricant seeping from the back of the timing case. It seems that the welding caused some warpage to the aluminum case, the high pressure oil pumped by the oil pump is finding a way out right where the back of the timing case is screwed onto the engine right side where the oil comes out of the oil pump and right into the timing case to enter the tensioner. I need to fine me a sound aluminum case and replace mine because the mechanic tried attaching it 2 times, but the oil still leaks out losing some 2 liters for a distance traveled of 80 miles. So, what I need most is to know what engine is mine? On what American vehicle it is basically used? Some Chevy, Oldsmobile cavalier may be, or perhaps a sports car with a Turbo feature may be.

It is a 4-cylinder QUAD4 DOHC engine, same as the one used on the Transport automobile but mounted on a Grand Am Model 1995 automobile except that its timing gear is different, having a 2-row chain with 2 row sprockets (both camshafts, water pump and crankshaft). If you focus on the second image you would notice how the lubrication oil vent is located on the timing case side facing front while in typical QUAD4 DOHC engines the lubrication oil vent is a metal pipe(tube) protruding from the center of the timing case cover that is shown in the first image. Here, my mechanic did cut that tube off, weld-sealed its opening on the cover because he made a mistake welding it there while not knowing of the vent port originally provided on the side of the timing case. The 2-row chain used here happens to be exactly the same as that used on too many models of Mercedes cars engines, same number of links, same design 100%. All I am after here is to know: What vehicle uses this QUAD4 engine with 2 row chain? Once I know that I would be able to order a sound timing case to replace the one I have after it endured warpage due to welding a fracture.

Not to my knowledge or imagination too. The timing chain that was included as an image within my starter question is a 2 row chain, not single. here, you will find 2 images for :
1. The single row assembly( timing chain, 2 camshafts' sprockets and crankcase sprocket).
2. The 2 row assembly( timing chain, 2 camshafts' sprockets and crankcase sprocket). Needless to say, the timing case body itself(aluminum casting) has the respective water pump sprocket(gear) accordingly, as to fit each assembly.
It looks like a QUAD 4 DOHC engine meant for a turbocharged engine may be, or why did they use a 2 row chain?
As told earlier, the 2 row chain is exactly the same as the chain used in too many models of Mercedes( A, B, C & S family). The 3rd image is for a Mercedes Timing Chain, ( https://www.heavydutypros.com/mercedes-timing-chain-double-row-39977094.aspx ).
The attached images can show you the parts of the assembly, part against part. You can see that the guides themselves are broader with the 2 row chain.

Kindly clarify more on this query (I wonder if you can install the signal timing chain setup? ). Meanwhile, I am attaching a video and images for the timing case after we disassembled it yesterday, FYI.