I am trying really hard to find out what can replace or is just alike for my 55 buick roadmasters steering gear box. I have been told a 55 century or a 55 riviara will inter change. Please can anyone help me. :confused:

Here is what the Hollander Interchange manual for steering gear says:

Buick '55 50 series (Super) and 70 series (Roadmaster) interchange. Note: '55 Buick 40 series (Special) and 60 series (Century) whole assembly from steering wheel thru pitman arm fits.

So the easiest route would be to find one for a Super or Roadmaster. Just another note, the term Riviera refers to a hardtop car, which was available in any series.