[Figuarus]

The basic air box does not have a controllable flap to direct air. The only heat on/off is a flap in the plenum that closes and doesn't allow heat to be directed into the cab. The true heat on/off option heaters had a valve inline with the 5/8ths hose and had a cable that opened and closed it.

I'm going to swap out the core later today, and if it's not a significant improvement, I will end up modifying the box to allow air to be pulled in from around the passenger side exhaust manifold.

All that waste heat has to be good for SOMETHING, right?
KJSR, I will call you up sometime this next week, or next weekend.

thanks for the offer!