Steering wonder related to having correct idler arm for 1967 GT 500?

Hi All,
I have been experiencing a bit of highway speed drift or wondering on my Shelby. The car seems to at times, have a mind of its own. I've heard of this complaint from many other folks too.

I am on a quest to minimize or better yet, eliminate this. I starting by adjusting the steering box and the PS spool control valve. I believe that I have these adjusted well. I believe that the front end alignment is ok and the tires are all new.

After a close inspection of the steering linkages I found a small amount of vertical play in the idler arm at the connection of the body bracket and the idler arm itself. Everything else looks good. This 1967 GT 500 has power steering. In researching a replacement idler arm I see a few different types out there. The one currently on the vehicle has a ball joint type of pivot connecting the body bracket to the idler arm itself. From what I've seen out there, I think that this is the wrong type of idler arm.

Other recomended types of idler arms have a bushing type of pivit there (body bracket to arm). With this type of design, the bushing has inner and outer steel liners that get locked in in such a fashion that the the rubber flexes back and forth causing a self centering action on the steering. This sounds like a good thing to me. Another point of interest, there's two bushing sizes. Smaller for manual steering, and a larger one for power steering.

Seems to me that the "power steering" type idler arm should be of the bushing type, perhapse the larger one because the system has the power to overcome the bushing resistance. Again, I'm talking about the connection between the body bracket and the idler arm itself.

A few questions:

1) What type of idler arm was original installed on 1967 GT 500's with power steering from Shelby American?

2) Whats the part number for this, and was the number marked on the part at all? I found one that may be the original that I could rebuild but it has no markings on it.

3) Whats the advantages of the ball joint type of design if any, might they just be cheeper to make...?

Any comments on usage or experiences with these different types of idler arms or improving the handling of these vehicles is very welcome. I want my Shelby to handle as best possible while trying to preserve its originality.

Thanks in advance,

Steve67

 

I believe it to be set at more like 2+. I'd have to get it on a rack to really know. The manual that I have recommends 1.5+ for caster.