Applicationt: 
Auto
Production Description:
1. Exported to USA, CANADA, Center American. 2, Good quality, 3.Hard package, 4. 2 Horizontal delivery ports
R-5 relay valve:
1. Delivery port: 2, 3/8 in P.T.
2. Reservoir Ports: 2, 1/2in P.T.
3. Control Port: 1, 3/8in P.T.
4. 6 psig Cracking Pressure
some parts number reference:
PAI/EXCEL: LRV3639/EM36390
BENDIX: BEN 229467
MID: KN28060
NAV: 455975C92
it is suited for Mack truck, and exported to USA, CANADA, Center American market