3.8 engine interchange

I am exploring my options in dealing with my recently acquired 1982 380SL. I have what I assume to be a serious connecting rod problem (knock). I have searched the archieves looking for interchange information. I found out that the 3.8 engine block and the 4.2 block are the "same" Is the 4.2 block a candidate if I would decide to replace my engine with a used one?

A local wrecking yard has a 3.8 engine from a 1982 380 SEL. They suggest that the only difference between that engine and the one in my '82 380 SL is the oil pan and pick up tube. Swapping out those items from my engine would be the only change to drop their engine in my car. Is this correct?

I guess I would like to know what engines I can expect to be a replacement for my current one. I might add that this car is a decent original car with 133,000 miles showing some wear- in my book a "driver".

I will be removing a cam cover tonight to see if this particular car had the double row chain upgrade. I would assume that I could swap out that set up (if so equipped) when swapping engines (if the replacement is still the single row).

I appreciate anyones help on this information. I apologize for being a newby, I will try to "get up to speed" as soon as possible :-)

Randy