83 C30 2wd Heavy Duty vs Non-Heavy Duty Front Suspension?

[EricU]

I have an 83 C30 2wd that I am going to lower using one of Todd’s at Lowboys static kits, add 22” Alcoas and so on.

I am trying to get the front end suspension piece, ball joints, tie rod ends etc before my kit shows up so I can rebuild the front end and not have to wait for parts.

I want to purchase all Moog parts and when I look online, they list both a
Premium OE Replacement; with Heavy Duty Suspension; Bolt On Control Arm Shaft
Premium OE Replacement; without Heavy Duty Suspension; Smooth Control Arm Shaft

I do not have the truck here right in front of me right now, what is the difference between these two?

Apparently, the Control Arm Shaft is either smooth or a bolt-on.

What is the “Heavy Duty Suspension” on a C30?