I believe bartamos is correct, early military truck, part of the fording system which includes a PCV valve connected to the intake and other components of a closed system.
Likely doesn't belong on that engine. Looks cool though.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine