I just replaced the belt on my 1936 Ampico B.  I used a Gates Truflex
again after consulting with Craig Brougher.  The original belt, in red
rubber with the markings "NRA - We Do Our Part", was on the unit when
I got it in 1968 but crumbled in 1970, about a 32 year life.

The Gates belt put on in 1970 (32 years again) looks perfect, but is
now stiff and would thump from flange to flange on the pump pulley,
sounding like a knocking pump, but it was completely out of phase with
the pump and everything.  It took me three years to figure out what the
problem was.  Alignment?  Tension?  Nothing else was out...

Karl Petersen
Rushville, Illinois