Re: Volvo 270 Steering arm bolt
If you are asking about the steering fork spindle arm pinch bolt, this is a grade #8 3/8" UNC bolt (not Metric). The threads must fully penetrate the spindle arm female threads and have enough threads to not bottom out.
You'll want a hardened 3/8" SAE washer on the head and you will want the threads greased.
The OEM manual should give you the torque spec.