OEM Pulley Setup

[eric8]

Anyone have a mid to late 70's model C10 that has an original power steering and alternator only belt setup (non a/c)? What I'm trying to find out is if that setup originally had a double groove crank pulley and single groove water pump pulley.

I'm thinking one belt should be routed through the one groove on the crank pulley, over the water pump, and then to the alternator. The other belt i'm thinking goes in the other groove of the crank pulley directly to the power steering pump.

The reason i'm asking is i'm trying to add power steering to an alternator only truck and figuring out what pulleys I need. I've seen some 70's GM cars where both the crank and water pump pulley are double groove, with both the power steering belt and the alternator belts driving the water pump?