Fitment checked before dispatch
24-month warranty
Returns to a US address
Quote reply within one business day
Photographed in our warehouse — the part you receive is the part shown.
Progressive load support that keeps the factory ride height.
Pricing for this part is being published system by system. Add it to your quote list and we will confirm price, stock and lead time by email, usually within one business day.
A progressive helper spring takes the sag out of a loaded rear end without turning the truck into a hay wagon when it is empty. It works alongside the factory spring, engaging as load comes on, so the first inch of travel still feels stock.
| Type | Progressive helper spring |
| Position | Rear |
| Mounting | Bolt-on, no drilling on listed applications |
| Included | Mounting hardware |
It is an aftermarket part engineered to the specification for SSF-604-40. It is not a genuine OE part and we are not affiliated with the manufacturer. The cross-reference tells you what it replaces.
Match the cross-reference numbers on this page against the number on the part you are removing, or send us your VIN / engine model and we will confirm before dispatch.
24 months against manufacturing defect — material, workmanship and function. Wear items and damage from incorrect installation are excluded. Claims go to a US address, not overseas.