In my experience the cracks at the steering column mount to the dash is because the front body mounts and maybe also cab mounts have rusted too much and collapsed. Now the steering column is having too much stress on it because it’s bolted to the frame at the bottom and has no flex joint. It’s trying to hold the whole cab in place with normal road driving chassis flex. I suggest you examine the main cab and front sheet metal mounting points.
I bet your brake and clutch pedal holes on the floor are worn oval or elongated too.
-s
