Steering Box Info

 

So far, I've come up with the following information on steering boxes. This information doesnt account for internals, such as firm feel or steering ratios, just basic interchangability.  Currently, there isnt much chance of finding a police power box or quick ratio manual in the local U-Pull-It, so most performance boxes would be purchased aftermarket anyway.
 

All steering boxes will physically bolt to all K-frames. The physical length of the boxes only differ between manual and power, therefore, steering columns only have two lengths - one for manual and one for power. Although you'll probably get a new one, the coupler block between column and box is specific for manual or power.

The compatibility problems with different boxes largely boils down to output shaft, or sector shaft size. First, there are two sector sizes, simply known as large or small sector. The large sector, just above the splines as it exits the housing, measures 1.22". The small sector measures 1.11".

62-76 A-bodies, 62-72 B-bodies, and 70-74 E-bodies all used the same manual box. Most of these boxes used bushings throughout, however, the B-body V-8 units were built for more abuse and used bearings internally instead of the bushings.
All manual boxes used a small sector shaft with the exception of C-bodies and vans to 1988. The big cars and vans used a large sector, presumably for added strength. It's also assumed these boxes used bearings instead of bushings.

Power boxes before 1973 were mostly small sector. I havent been able to find evidence of large sector power boxes before then. From 1973 to present, all power boxes were large sector. There is very little physical difference in power boxes except for the input housing for the lines - the shape of this housing changed through the years, and through the various models, but all the input housings are interchangable.

Pitman arms are covered in "Linkage", but there is an issue related to both. All pitman arms have 3 splines left out so the arm can only be installed one way. This is referred to as clocking, and pretty much ends the thought of using a pitman from another chassis. For instance, the c-body pitman arm is similar in length to the fast ratio arm on the T/A and AAR cars. However the clocking is different and cannot be positioned correctly on B or A bodies. It's possible you can modify a different pitman to work, IE - file or grind the extra spline and bend it to the correct position, but it's definitely not recommended. Steer and Gear, and FirmFeel both offer universal fast ratio pitman and idler arms that work out of the box. Of course, these arms move the centerlink back, causing a possible interference with headers. The aftermarket arms also have no locating spline, so you have to find center yourself.
 

   

Notice the various differences between the two castings. Most notable is the cover plate, which makes it possible to tell the difference by just glancing under the hood in the junkyard.
 

In addition to this information, its fair to give warning to the uninitiated, that the single most stubborn part to remove from your car is going to be the pitman arm from the box. An actual pitman arm puller is highly recommended to ease this task.

Good luck, and again, if you have anything to add to this page, drop me a line.

One item I'd like to know about is the possibility of using a large sector manual from a van to replace a late power box. This would make the power to manual conversion a bit easier, but I'm unsure about the pitman arm clocking to know whether the late a-body pitman arm will work on the van box.