One of our work trucks has a leak. Its an aluminum housing bolted to the fire wall looks like a regulator mabey or something like that. Its hard to explian but if anyone can hook me up with a link to diagrams or something for the air systems on them. Not shure of the year L8000 single axle flat bed.

 

you could try something like on the arvin/meritor website or the midland/grau or bendix website. I did not check myself, but something could be there. I worked on plenty of the L series fords, but just not sure off the top of my head

 

Possibly the goveroner? treadle valve? i'm not overly familiar with the L series.