DH478 Toroflow-powered 1972 GMC Napco 4x4 K5500

[kscarbel2]

On 2/6/2026 at 11:30 AM, BOBWhite said:

Have one of those giant GMC gas V6s sitting in a truck, don't remember what ci it was. My uncle told me that the gas v6s were basically built to be diesels so they'll last forever. Must not have been a very good diesel though from what I've heard.

Oh the topic of air-cooled Duetz; never knew you could get them from the factory in trucks here. Up until 96 you could get them in gleaner combines but they were hated by most. Twin turbo air-cooled V8 was just too strange for farmers, they had to be kept CLEAN which isn't easy to do on a combine. Parts and service were also terrible so many got junked or cummins swapped if they really like the machine. At least they sounded cool 

In light and medium trucks, the Deutz are water-cooled.

I had good experience with water-cooled Deutz in 863 Bobcats.

My Liebherr A912 rubber-tired excavator did have an air-cooled Deutz and was absolutely trouble-free.

[BOBWhite]

Some of the newer John Deere choppers use v12 Liebherr engines. Never been around one 

Took a look at that GMC V6 this weekend, 67Rmodel was dead on with the location of the number but it took some scraping to read. 401M is what it said but still not sure what M or "magnum" means. It would be a cool motor to swap into something but the Allison auto trans in it is way too huge for a pickup. 

[67RModel]

9 hours ago, BOBWhite said:

401M is what it said but still not sure what M or "magnum" means.

Info is sketchy at this point but the magnum engines were a further refinement of the bigger 60 degree V6s for heavy truck engine use. The had bigger carbs, A different intake port design, larger valves and possibly a different cam profile all geared toward higher torque and horsepower figures. 

[RoadwayR]

18 hours ago, 67RModel said:

Info is sketchy at this point but the magnum engines were a further refinement of the bigger 60 degree V6s for heavy truck engine use. The had bigger carbs, A different intake port design, larger valves and possibly a different cam profile all geared toward higher torque and horsepower figures. 

That is correct.  GMC made 'Magnum' versions of the 351, 401, 432, and 478.  There was also a special 351E version offered in pickups for a few years that had the 'Magnum' parts on it.