how do i replace complete steering column on a 1997 mercury couger ?

you can, but are you good at keepin' track of stuff? I always lose the fasteners, then visit the seven planes of hell tryin' to piece it back together...Okay, you're going to have to see what needs to come off to gain access to the mounting bolts, probably am going to have to tear near half the dash apart, then on the firewall side there's a "soft" steering coupler that is kind of fussy too, be sure to keep the parts and pieces of that in a special place too~....so in conclusion, yes it is possible with an eye towards organization, skill with fasteners and the right set of sockets to get deep inside the dash~

would take a lot of pictures~

Dear Judge Roy, Thanks for answering my steering column question! Roy, I did get the whole steering column replaced, but it took me 2 days as I'm 6' 1" and there's not much room underneath the dash! Only had to remove one big piece of the dash under the steering wheel, then 5 bolts plus 5 electrical connections and out it came ! The hardest part putting it back together was re-connecting one of the electrical connections and I have the scratches and bruises to prove it ! LOL Again I want to say THANK U for responding. Take Care, John

perhaps I exaggerated, a bit have never been lucky enough to have to do a replacement, but the biggest hassle seems to be getting the ignition key to match all the other keys so that perhaps a round-top trunk key, but the same damn key, no one wants to have a bunch of useless keys to contend with- you are one ambitious fellow, kudos to you sir~ thanks for rewarding me with reputation points, am quickly becoming Guru No.4 but is bitin' into my free time and most questions could be answered with a search engine that isn't tryin' to sell you stuff~ thanks again, John---it's been a pleasure dishin' with the sensible advise~