Me too, hoping its as easy as it seems.   Worst case scenario I end up transfering all the new bits over to the XF's block and suck it up with running cats and all that shit.   IIRC the crank, pistons and rods and other bits should transfer over. I need a new cam for the conversion so that wont be an issue.   Hmmmm starting to think my friends might be on to something with going for a 393 clevo and TKX...

I took my power steering box out 6 weeks ago, but I was going to elaborate more on that in my own thread and try leave this to stay more on topic 👍   Anyone have recommendations for a reco power steering box? Or at least where to avoid...

haven't seen that done before, so it will be interesting to know how it goes.     

there's very little movement in those 3 steering box mountings from memory.  

Well I found a machine shop willing to convert my pre xflow block to suit a crossflow head so I can use the rebuilt bottem end with a crossflow cam and the EFI head and valve train.   My pre xflow engine is a 72DA so I can avoid having to use emission gear with the later EFI setup...winning   Apparently the mods to make the xflow head fit is pretty easy to do, and as I have to disassemble the block to clean up a few scuffs on the bores it's worth while getting the mod done and the block decked to suit the upgrade.

Well I can't attest to having bent a drag link before... but in my case I just wasn't sure why it didn't line up well enough...after reading this thread and others it got me thinking that when the drag link is tightened to the pitman arm, you could see the alignment of these pins with idler removed, then rock the loosened steering box back and forth to see how close to straight that you can get it, and then tighten box...maybe...  

pedders picked my drag link once, quoted like $800 for a new one (20yrs ago) i said i've got 2 more at home (used to buy a car when i needed parts) fitted another, came back.. same thing.. (whatever they were crapping on about at the time i am not sure. but i brought the other 2 with me and they were all the same.. just ran with it, surely they weren't bent?)

being you had different angles, that is interesting though.  wonder if/how they get bent perhaps jumping a gutter or similar?

Personally, I'd give one a go... reducing that up and down movement should only help, as the other side is held firmly by the steering box and pitman arm, so should the idler arm... My XF van has always been really good in the steering with no need to replace stuff regularly, and in 26 years I'm on my 3rd idler arm which is a Super pro polyurethane one, which has shown to have the least up and down movement of any that I have used, and best I've used... It currently lives in the XG van, as I have swapped over the whole (outer tie rod to outer tie rod) to see if any difference could be seen (due to considerations of XG having a possible bent drag link). The XG had a very flogged out steering and suspension when I got it, and this process only concluded that I don't have a bent drag link... My XF has the mounting pins (visibly) at the same angle when idler arm is removed, but the XG's pins are noticeably not at the same angle, making it hard to even get the idler arm back on, so against advice to move the  chassis mounted pin, I marked it and moved it, but couldn't move it as far as needed to line up with the drag link pin, but was easier to get idler back on... I feel that the final position of the steering box (due to a little movement in the bolts and holes) may help with the alignment of the drag link pin for the idler... The XG front end rebuild is a story for my thread and not yet finished as I'm looking at a replacement box...

Ok so I have driven the car today, for about an hour, on all different road types. Freeway, residential and some more back/ruralish C roads.    Conclusion?    The car is as good as I think I can get it. Is it 100% gone? yes and no. 🤔 - Yes because it does go away and its perfectly smooth - No because it will randomly come back and go away again. now its not as severe I don't think. This was on a perfectly groomed freeway, where I guess any imperfections I feel because the road surface is so smooth.    How does the car drive?  Really good. The steering feels good, direct and responsive.  The brake shudder is 99% gone now.  The car corners really nicely now.    So now that I have done all of this work, I have a few conclusions.    On a perfectly groomed freeway, i feel the smallest of imperfections, because the front end is so tight now. The shake, not as bad, does come and go on the perfectly smooth freeway, and is very noticeable because there is no rough or uneven surface giving me feedback through the wheel. so whats causing this? out of round wheels and/or tyres moving in and out of phase of balance? It appears to get a little upset after hitting a bump...so bump steering setting it off? weird...   On some back roads, in this case for Melbourne people. I drove out along Lysterfield Road, onto Wellington Rd up to Clematis. Sitting on 100km/h for part of that, and it didn't seem to give me any shake that was not from the rougher rural road surface. So I am seeing a fair bit of bump steer it seems. Not surprising given the geometry in the front end.  From Clematis I turned left and drove across to Belgrave and down to Ferntree Gully. lots of twisty roads to try it out, and yep it felt great, no shake while cornering when the steering is under load, precise and direct feel to it.  So oddly, the car seems much happier and seems to handle being on a rougher surface rather than a smooth freeway environment.  Next day I have off, I will head off for the day, and spend a solid day driving it somewhere and see how it goes on a longer trip, see in what environments I can or can not fault it.    The last thing I want to test, but not today, is putting the wide 13" steelies that are currently on the back, on the front, and see how, if at all, the car is affected by a change of wheels. the 13s on the back are the straightest two 13s i have, and the 15s on the front are the straightest pair of wheels out of the whole lot. the 13s on the back are the ones I always had on the front when I was running all the 13s. So I would like to go back to trying them and see how the car goes then.   now previously I had said that when I finally sort this out, I will make a decision on what wheels I am keeping on the car, and fit new tyres.    This leaves me with a conundrum.    I love the look of the 13x6" Lotus Cortina wheels. But, none of them are perfectly straight, and 1 of them has been modified to have a different offset. So Im not sure I want to keep trying to get them fixed and running true when it may no longer be possible.  I can replace them with reproduction ones. I'd be looking at, in round terms about $1000AUD landed. then tyres on top, which would be something decent. nice and grippy. Some Yokohamas or Toyos etc.    Or; I go back to running the 13x6" RS 4 spoke Alloys. I also like them a lot, but they don't look as aggressive or "racy" as the steelies. The alloys need restoring. Quoted $300 a wheel to be rolled, painted, diamond cut. so $1200 plus tyres.  Or I can also replace them with a brand new set of reproductions, at the same price as getting the originals restored.    The 15s are not really going to ever stay on the car. I had the idea of putting some nice sticky track tyres on them and use them for the rare time i would take the car to a track day, but yeah not worth having them sitting doing nothing really.    So its between the 13s, and I really don't know what to do.     

that's pretty interesting.  I've watched mine in the past move a fair bit up and down in the bushes (new rubber/nolathane) when on a wheel alignment machine. and wondered if they would even work with roller bearings in a falcon. 

Toyotas (hilux/landcruiser etc) have beefy units that seem much more durable and i wonder if it's more due to the setup than the actual parts, (like, do they move up and down in the steering arm travel like a falcon with bump steer type movements?) 
I can't see Me owning another PRE AU even now, but it would be interesting to hear @Thom and @SPArKy_Dave thoughts on a roller bearing type idler arm,

I'd have assumed it will still need to be bushed with rubber, and although might be smoother to turn, it would still wear out the bush from the same movement the others had.