I was reading this post about aligning the steering box and I have a couple of questions.

With the steering wheel centred my car drives straight but the steering box alignment is slightly out (It does seem to feel like you have to turn it more in one direction than the other for the same amount of movement). If I'm understanding that post correctly to fix this I need to first disconnect the steering UJ from the box and align the wheel so that the wheel and box are centred, then adjust the drag link so the car drives straight with the wheel and box still centred. Is that correct?

Sounds like you've got it. Centre the steering box then centre the steering wheel. Once they are centred you can adjust the drag link so the wheels are straight too. You'll probably find that the drag link takes some shifting, when I did mine it involved heat, Plug Gas and a pair of Stilsons with a 6 foot length of scaffold pole slipped over the end before it started to move. My steering wheel is out, or at least the upper steering column is out, as the indicators cancel at a different point depending on whether I'm indicating left or right. Doesn't seem to have done the rotary coupler any harm although mine only deals with the horn and airbag, none of these fancy buttons on the steering wheel for plod.

Something I have to do for mine too.

But given that a Lemfoder drag link assembly cost me £46 + VAT from Island 4x4 back at the end of May it hardly seems worth battling with an old one. Joints are bound to be well worn too and I've seen similar broken during the hit, heat and heave with added scaffold pole process. Just what you want on Sunday afternoon when you need the beast to get to work on Monday!

However I tend to price my time out at around half garage rate and figure I'm ahead if I spend less than that on new parts. So usually plenty of wiggle room for new "not necessarily essential but so much easier to handle" than the "rusty but serviceable" bits that came off. At my age do it once, do it right and do it fast is attractive.

Different if its just tweaking recent replacement of course.

Clive