Having made several steering wheel changes on 50's, 60's and earily 70's GM cars I can say the Nut goes on easily down to the wheel. A metric nut will or might JUST start and become tight/stuck. Don't crank it down if it stops just short of 1/2 thread as it may very well be metric. Any idea what year the column you have is from and the year the doner nut is from? I take it you don't have a thread chaser/tap and or die that large to gently run the column thread and doner nut? Say the nut and column are compatable but the nut won't start or run, If the column was laying around your garage you may have bumped the thread. Take a close look at the thread on the column as it may be squished and won't accept a nut. You can take a SMALL file to the thread if it is damaged and removed the smashed thread and allow the nut to run down. Also check with NAPA, they have books on just about everything and may be able to give you a heads up on what you need and even get you a new nut.