IROC Steering Box Modification

This project involves changing the stock power steering box for a 3rd generation IROC box. The steering on the car can be a little vague and requires a lot of attention as it tends to wander. Since the car is 48 years old and the steering box is original and has never been touched, it's time to firm things up a bit.
The new box is one I bought off ebay about 5-6 years ago, but never got around to installing. It was advertised as being from an IROC, which would make it one of the more desirable ones. I don't remembered if it had the YH ink stamp that would indicates an IROC box, but we'll see. It can't be any worse than what's in the car. Besides, there's an 88 IROC project gathering dust in the garage, and I can always steal the one off that.
1stGenCastingNumber.jpg
The casting number of the original box is 5691676.
3rdGenCastingNumber.jpg
The casting number of the 3rd Gen box is 7826692. This doesn't necessarily mean the box came from an IROC though.
SideComparison.jpg
This view shows the significant difference in the Pitman Arms. They are oriented opposite each because the steering box in the 1st gen is behind the front axle while on the 3rd gen it's mounted in front of the front axle.
1stGenInputShaft.jpg
This shows the measurement of the input shaft on the 1st gen box. I believe it actually should be 13/16". I'm not sure I should trust my Harbor Freight caliper...
3rdGenInputShaft.jpg
This shows the measurement of the input shaft on the 3rd gen box. I believe this should actually be 3/4". The size difference is important as it means I will need a different rag joint than was used with the 1st gen box.
TopComparison.jpg
Here's another view of the new and old boxes. One other difference you'll notice is that the old box has provisions for 4 mounting bolts, though only 3 are used. The new box only has provisions for 3 bolts.
1stGenHoseFittings.jpg
This view shows the hose fittings for the 1st gen box. These are SAE threaded and accept the flared ends of the hoses.
3rdGenHoseFittings.jpg
These are the hose fittings on the 3rd gen box. They are metric threaded and will need adapters in order to use the original hoses.
3rdGenPitmanArmNut.jpg
The pitman arm on the 3rd gen box will need to be removed. This is always fun... Measurement shows it to be 1-5/16", or about 33mm. This will be a hard socket to find.
PitmanArmRemoved2.jpg
After a lot of grunting and groaning trying to take the nut off using the only tool I had that fit - an adjustable wrench - I finally gave up and brought it down to the local garage where they removed it for $10. A bargain considering the time I wasted on it.
NewPitmanArm.jpg
I got the new parts ordered and they started to arrive. New pitman arm, Moog K6582, $58.32 at Amazon.
NewRagJoint.jpg
New Rag Joint, Dorman 31011, $47.97 from Summit.
HoseAdapters.jpg
Hose Adapters, CPP 605SOL, $15.97 from Summit.
PitmanArmCompare.jpg
The new pitman arm is a bit longer than the original, I hope that won't be a problem. The difference is about a half inch.
RagJointCompareFront.jpg
RagJointCompareBack.jpg
A comparison of the original rag joint and the new one.
OldRagJointSize.jpg
NewRagJointSize.jpg
The new rag joint is also a bit bigger than the original one.
TestFitParts1.jpg
TestFitParts2.jpg
Checking fitment of the new rag joint and adapters. Everything seems to fit fine so far.
Getting things back in the car proved to be a major project and took several attempts with a lot of swearing (and beer). The box wouldn't go in without removing the steering wheel, or at least getting it loose enough to slide back far enough. Even after that the steering wheel wouldn't go back in far enough to line up with the 3 bolts under the dash that hold it in place. It seems like maybe the new rag joint was too thick.
Here's a comparison of the difference in thickness between the old and new rag joints. It doesn't seem significant enough to make a difference.