Apex Chassis KIT370-STL ProLock Complete Steering Kit — Heavy-Wall DOM Steel | Black Powdercoat | 2005–2016 Ford F-250 / F-350 Super Duty 4WD | P221 | SRW & DRW | 2–6" Lift | Gas & Powerstroke Diesel

Maximum impact resistance. One kit. Geometry locked permanently.

Factory tie rod and drag link components on the 2005–2016 Super Duty were engineered for stock-height pavement driving. Lift the truck 2–6 inches, add oversized tires, and push it under heavy trail impacts or extreme towing loads — and that factory linkage flexes, bows, and permanently deforms. Alignment walks out. Directional control degrades. Death wobble triggers.

The Apex Chassis KIT370-STL is the absolute engineering solution. A complete maximum-duty DOM steel tie rod and drag link assembly with the ProLock mechanical keyway system — engineered specifically for the 2005–2016 Ford F-250 and F-350 Super Duty 4WD P221 platform at 2–6" of lift. For the builds where aluminum reaches its limits — dedicated rock crawlers, heavy commercial tow rigs, and oilfield working trucks where the linkage takes direct hits and the front end cannot flex.

Section 1 — Comprehensive Sizing Matrix

Why DOM steel over aluminum on this application: While polished aluminum delivers exceptional performance for daily drivers, highway tow rigs, and trail builds where flex memory and weight reduction are the priority — thick-walled DOM steel provides maximum pure resistance to gouging and permanent bending from sharp rock contact. The DOM process eliminates the internal weld seam and produces a uniform wall thickness that resists the localized crushing forces of direct rock strikes that aluminum cannot handle at the same cross-section. For dedicated rock crawlers, oilfield working trucks, and extreme commercial towing applications — DOM steel is the correct material.

Unsprung mass note — read before ordering: At 61 lbs combined this is the heaviest, most robust steering assembly in the Apex P221 lineup. Factory and light-duty replacement shocks are not optimally valved to dampen these tracking forces over harsh terrain. Upgrading to heavy-duty performance-valved shocks and an upgraded steering stabilizer alongside this kit is strongly recommended.

Section 2 — Critical Compatibility

✅ This kit fits — P221 solid front axle 4WD

❌ This kit does NOT fit — read before ordering

P221 vs P558 generation split — critical: Ford completely redesigned the Super Duty steering geometry between the 2016 and 2017 model years. This kit fits the P221 coil-sprung platform only — 2005 through 2016. If your truck is a 2017 or newer, stop here and see the KIT375 series.

⚠️ BDS Adjustable Trackbar incompatibility: The oversized dimensions of the ProLock components in this kit can cause contact with BDS adjustable trackbar adjustment sleeves during deep suspension cycling. If you are running a BDS adjustable trackbar, text (469) 407-7538 before ordering — we'll verify geometry clearance before we ship.

⚠️ Camber note for alignment shop: The 2005–2016 Ford F-250/F-350 P221 platform runs a solid front axle where factory camber is entirely fixed and non-adjustable without aftermarket offset ball joints. Post-install alignment corrects toe and centers the steering wheel — camber remains fixed. Inform your alignment tech before the appointment.

Supporting mod requirements:

• Lifts 2–4": Direct bolt-on with factory pitman arm. No additional hardware required beyond the kit.
• Lifts exceeding 4": A track bar relocation bracket is strongly recommended to maintain parallel operating planes between the track bar and drag link. An aftermarket dropped pitman arm may also be required. Text (469) 407-7538 with your lift brand and pitman arm setup and we'll confirm before we ship.

Section 3 — Before You Buy — Questions We Get Asked

Q: Why choose DOM steel over the polished aluminum Apex kit?

Both cover the same 2005–2016 P221 platform with the same ProLock geometry correction. The aluminum kits deliver exceptional performance for daily drivers, highway tow rigs, and trail builds where flex memory and reduced unsprung weight are the priority. The KIT370-STL DOM steel kit delivers maximum pure resistance to gouging and permanent bending from sharp rock contact — the correct choice for dedicated rock crawlers, heavy commercial haulers, and any application where the linkage will take direct violent hits against hard surfaces. Text us your intended use and we'll confirm the right kit.

Q: Does this fit my 2015 F-350 dually?

Yes — F-350 SRW and DRW both confirmed on the P221 platform. F-450 and F-550 commercial chassis trucks run wider commercial front axles with different taper dimensions and are not compatible.

Q: Will this fix death wobble on my lifted Super Duty?

Yes — provided ball joints, track bar bushings, and steering box are in serviceable condition. The ProLock mechanical keyway system and thick-walled DOM construction eliminate the factory compliance that permits front-end tracking to oscillate out of control. Plan for performance-valved front shocks and an upgraded stabilizer alongside this kit to properly control the added front axle mass.

Q: How hard is this install and what will I need?

Intermediate to advanced difficulty due to the physical weight of the DOM steel components. Standard hand tools, a torque wrench, and a floor jack are required. A full front-end toe alignment immediately after is mandatory. ProLock jam nuts must be torqued to Apex specification to fully engage the keyway locking mechanism. Budget one garage session for the swap and one same-day alignment appointment.

The Obsidian Take

The KIT370-STL is for one specific Super Duty owner — the one whose truck goes where the linkage will take hits. Rock crawlers who drag the tie rod over boulder shelves on the P221 platform. Oilfield working trucks that earn their miles in conditions that would bend factory linkage on contact. Heavy commercial tow rigs pulling at maximum capacity where the front end cannot afford any flex. The thick-walled DOM construction with ProLock keyway jam nuts physically locks alignment against any terrain — the front end cannot walk, flex, or oscillate out of spec. At 61 lbs it is the heaviest assembly in the Apex P221 lineup, and that weight is the DOM steel doing its job. F-250 and F-350 SRW and DRW both confirmed across the full 2005–2016 P221 range.

This kit is not for daily drivers, highway tow rigs, or trail builds that don't involve direct linkage-to-rock contact — the KIT374-POL polished aluminum kit delivers better ride dynamics and reduced unsprung weight for those applications. It is not for 2017 or newer Super Duty owners — the P558/P702 platform requires the KIT375 series. It is not for F-450 or F-550 owners. It is not for 2WD Super Duty owners. At 61 lbs, factory shocks are not a sufficient complement — plan for performance-valved front shocks and an upgraded steering stabilizer alongside this kit. If you're running a BDS adjustable trackbar, text us before ordering — that combination requires manual clearance verification before we ship.

Product information is compiled from manufacturer-provided data. Obsidian Forged Auto Supply is not responsible for manufacturer-driven specification updates, metadata changes, or accuracy discrepancies in the foundational data sheets.

2005–2016 Ford F-250 / F-350 Super Duty 4WD. P221. SRW & DRW. 2–6" lift. Maximum-duty DOM steel. Performance shocks strongly recommended alongside this kit. BDS trackbar users text us first.