Starter Solenoid ???????? Help

[Eyegore]

On my sons 1982 c2500 2wd 6.2 Diesel the starter stopped working. I suspect it was the solenoid on the starter so I purchased a solenoid from Oreillys, there quite a bit $$$$ difference so you'll know why I'm trying this first. Now the old solenoid has two relays, one I believe for the battery (power) the others for the starter switch it has an "S" by it. Now my dillema, the new solenoid has 3 connections, the large main for power then two smaller ones one labled "S" the other "R", I know I need to connet the main and the "S" but is this going to cause a problem if the other relay is left unconnected, and what would I connect. If you can offer ant advice I would certainly appreciate it. I truly hate electrical problems also its 108 degrees here today.

Thanks guys.

Tom