OK...here's a picture of the manual-steering box mounted on my '69 F100:
...and here's a similar view of the '78 F150's PS box mounting:
First of all, you can see how they differ. The manual steering box is located much farther forward to the front, actually dead center on the front crossmember, with the Pitman arm facing backward, whereas the '78 PS box is farther back, almost against the Panhard bar bracket, and has the Pitman arm facing forward. Also notice the spacing of the bolts between the two...they're not the same, meaning some drilling would be necessary to mount the PS box in the same relative location on the '69. However, that's not going to be easy, since the inside of the frame rail of the '69 is boxed, and there's a curved section right where it needs to be mounted. Here's a shot of the '69 setup, looking down on it from the driver's side:
And finally, here's a shot of the inside of the '69 truck's framerail. The yellow arrow is pointing to the forward mounting bolt/nut.
OK. Now, to mount the '78 box on the '69 in the forward location (where the factory '69 MS box is currently located), I'd have to drill new holes. However, because the front crossmember is there, I have no access to the backside to put a nut. If I was to mount it there, I'd also have to flip the Pitman arm around 180 degrees to face rearward.
On the other hand, to mount the PS box in the rear location, where it was mounted on the '78, I do have access to the backside of the frame, but the framerail boxing is curved, meaning that some modification would have to be done to create a flat surface for the nuts.
Unfortunately, I neglected to look at the inside frame rail of the '78 after I removed the box to get an idea what the factory did, but I'm guessing it's a flat area there instead of the curved brace that the '69 frame has in that spot.
Anyway, at least we now know that it's not quite the easy bolt-on we've thought it was. So which direction should I go? I'm not really a mechanical-engineering genius, but I do know that there's the Ackerman principle to consider here...would changing the location of the steering box have any affect on this? The way I'm looking at this, the easiest way would be to simply cut out the curved frame brace on the inside of the '69 frame and weld in some flat steel instead...however, I'm open to any suggestions. Any insight into this would be greatly appreciated.
