Inside the box
Turning the wheel turns the input (worm) shaft. Balls rolling in a closed loop between the worm and the rack piston act as a rolling thread, so the piston moves along the worm. Teeth on the piston turn the sector shaft, which swings the pitman arm. In a power box, pump pressure acting on the piston provides the assist.
Identify a box: what to write down
Box makers describe their boxes with a short list of specs. Record the same things for the box you have, or the one you want:
| Item | How to check |
|---|---|
| Donor vehicle, year, 2WD or 4WD | The truck it came from, or tags and casting marks |
| Input shaft diameter and spline count | Measure the diameter and count the splines |
| Sector (pitman) shaft size and splines | Measure, count, and note any master splines |
| Pressure and return ports | Inverted flare or O-ring, and thread size |
| Rotation | Which way the pitman arm swings for a right turn (standard or reverse) |
| Turns lock to lock | Count with the box off the truck, or wheels off the ground |
| Mounting bolt pattern | Measure the bolt pattern and the box position on the frame |
Makers also publish pressure and flow ranges for their boxes. Match those to your pump.
"Saginaw-style"
You'll see "Saginaw" all over classic truck steering. It refers to the GM-designed recirculating-ball box family, and many replacement boxes are built to that pattern. For example, Bouchillon sells a "Saginaw" power box for 1972-1977 Dodge trucks, and Borgeson's box for 1980-1993 Dodge trucks lists a "GM" pitman shaft. Don't rely on the name. Match the specs in the table above.
Swaps and upgrades
- Same-family swaps: crossover conversions often use a 2WD-position box from the same year group. On 1978-1993 Dodges, the existing box can usually just move to the 2WD position (see classic Dodge).
- Quick-ratio and heavy-duty boxes: fewer turns lock to lock, or a stronger housing and sector shaft. Read the application list. Some aren't rated for heavy diesel fronts.
- Rebuild vs replace: seal and bearing kits fix leaks and some play. A damaged rack piston or worn gear usually means a replacement box.
- Pump and hoses: a box with different fittings or flow needs may mean new hoses or a matching pump.
Centering a box
With the pitman arm off, turn the input shaft to one stop, count the turns to the other stop, then come back half that count. That's center. Install the pitman arm in its correct position for that box, then set the steering wheel with the drag link. Follow your service manual and parts instructions for fastener specs.
Braces and mounts
A steering box is only as solid as what it's bolted to. Frame rails flex and crack at the box on many solid-axle trucks, and braces exist to tie the box to the opposite rail or add support under the sector shaft. Classic Dodge owners box or plate the frame, JK owners add sector-shaft braces, and Dodge Off Road makes steering box braces for later Rams.
Last reviewed 2026-10-19. General information only: verify with your service information and parts maker.