It was the radiator, partially cloggued, they were able to rebuilt the old
one as the lower and upper part were not leaking. The thermostat was put
back and the van properly bleeded, they are on the road again. They also did
a pressure test, engine running and engine stop, both test were successful.

Hot temp, heavy hill... it's when the cooling system is working the hardest.
The flow was not good enough. The original post was "Need input on radiator
problem", so i was right from the start. I have confidence on my engine, but
she made me doubt that! Sadly, that engine overheated a few time... that
proove one thing, the gauge in the dash of the early van should have a
blinking light when the needle goes to high.

Just si you know, just before, she had a drive axle that literally explode
damaging the outpout shaft of the tranny, some other Mex mechanic were also
able to fix that also. In the midle of nowhere.

Thanks for your imput and comments, i have learn, again, a few things.

Ben