Let's see

240D: 3250lb / 68hp = ~48 pounds per horsepower

617 turbo swapped GL350: 5467lb / 125hp = ~44 pounds per horsepower

It should accelerate slightly faster than a 240D which in my opinion is fast enough

Although because of a 3.27 axle ratio and taller tires in the GL you would have to stay in 3rd gear to get any acceleration on the highway

The OM616 was installed in a number of vans, delivery vehicles and motorhomes, some of them up to 8,000 pounds or so and they could all slowly reach 55mph. I don't see why the OM617 would be a problem.

My last motorhome was powered by a 4-cylinder Isuzu turbodiesel which is only slightly more power than a OM617 at 12,000+ pounds (140hp and 240 ft-pounds of torque). I had no problem keeping up with street traffic or freeway traffic. It may have even been able to beat a 240D in a race.

Dkr.

on a more serious note: If the engine is really damaged then your best bet is to find the same engine in a good used condition and have someone put it in or do it yourself.

or

If MBUSA steps up and helps with the cost of a new one then go that route

You might get lucky and get some love from MBUSA but I would not bet on it. Unfortunately they are now of the mindset that their products are disposable, and anything with a combustion engine in it is only a placeholder, until they go 100% electric in the next 10-15 years.

However there is the Copart or LKQ route to find another OM642.

Note that it is not plug and play however as you will have to use your existing ECU (or DAS will never let you get anything going) but you'll have to either swap over your injectors (don't mix up the cylinder assignments!) or code the new engine's injectors into the old ECU with Xentry.

And there were different variants of the 642 based on the platform so best to find the same year range and type vehicle as yours. For example on the SUVs the oil pan is split to allow the left front drive shaft for the 4matic to pass by. On the RWD sedans the oil pan is flat.

Best bet is to go by the 3 digits after the 642 in the engine type number.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech