Engine braking????

[talltom]

A friend of mine has a 96 chev 3/4t 4x4(with a 350) and just got back 
from
a hunting trip. This guy was a GM line mechanic for 20 years and 
has owned his own shop for over 15 years, and he insists that his
new truck does something so that once the brake is tapped going downhill
it will not under any condition gain speed. Neither he or the other 
mech can figuire out why, but both swear to it. 
  My question is is it possible that the guys at ac-delco have rigged
things to retard timing to the point that the compression stroke 
would be infringed up on as necessary for deceleration??? Makes me 
wonder if some wise ass has done a little abs system interfacing here????

  I realize that some of the company guys have non-disclosure agreements
to deal with, but I'd appreciate as much insight into this as is
pheasible!