After discussing everything for and against the conversion again over the last few days, we got to the heart of the matter:
Not that we done this before we descide to go with an engine swap... but before we had not a Donortruck with 360 HP to compare what we will lost
- the historical value of the M1008 will only be recognized in Germany if it corresponds exactly to the original. That means also with original engine, performance and equipment.
A complete remanufactored (Drivetrain, Frame, Suspension, Brakes...) M1008 in original condition without lifts and Hummvee wheels like ours can bring up to 40000 Euro, but only in original condition. We will have spent finally for finish complete Remanufactoring amount of 20000 Euro.
We would have waived the historical registration if we had gotten with the engineconversion a daily driver with high towing capacity and pleasant cruising speed. The 6.2 with 156 HP is absolutely not suitable for this purpose
If we would install the Duramax, will this be a "new" vehicle (not more GMC and not more M1008) and does not get a historical registration, which immediately reduces the value by 50%. The engine power would have to be throttled to 280 HP due to the weaker frame and suspension. With full engine power, frame reinforcement, high performance brakes and suspension would be required with the appropriate testing of a prototype for road registration. The cost of this cannot be estimated.
Our solution is called a second pickup

The M1008 will be completely rebuilt in historic condition, thus maintaining historic registration. To drive to meetings and to have a financial investment in a classic car because we don't want to sell him after now 25 years with us.
But since we also want to have a powerful daily driver with towing capacity, the GMC will stay. He was deregistered today to also disassemble him to the frame for the purpose of remanufacturing.
He is in the same condition as our M1008 before remanufactoring.
Typical surface rust on the frame, rubber parts hardened, some dents from former owner... and as it is not a historical vehicle we can go on with any Customizing the Truck we like to do
This is the historical appearance of our M1008

we are only missing the troop seats and the cover
unfortunately the military trailer hitch is here not allow to use on the road
So the military trailer can only be use if i change the military hitch to a rockinger.
Maybe if we can got a good trailer... until this time it is not necessary