I have bought and used literally thousands of Rigid wrench parts to go on the hundreds of wrenches. In fire protection we use mostly 8" and 24" wrenches on the pipes we install. We carry a 10" in our pouch. A 14" steel wrench is used on the Rigid 300 power machines for use in making on fittings to pipe we threaded.
The jaws, heels, pins, and nuts are expendable and wear out. The handle is the only part that you need turn in under warranty - so save nuts and heels when returning for warranty. The jobbers give you a complete new wrench.
Because your nut is split, I think you have a good chance that they would replace it for free.
The red wrenches are bulged at the end, as are some of the black ones. The bulge hangs the wrench from a Rigid Tri-vise in the slot. It is much easier to hang that way rather than trying to put the hole over a pin.