If heavy duty means “lets you carry more weight in your bed and tow more” do not do it unless you actually have weight in your bed or tow a lot. To do this, the springs have a higher spring rate which makes the ride very hard unless you’re loaded.

Get the part that matches OE for your VIN.

I would trust rock auto, but your mech might charge extra if fitment is off.

If it were anything but a Toyota, I’d say to avoid the OEM premium, but I’d get it in this case. But not from a mechanic, either. You can almost certainly find then for a lower price and install yourself. Leaf springs are like 3 bolts