I have just started installing the rear axle parts on my 1972 Devon resto. The torsion bars looked visually identical so I installed them and fitted the driver side spring plate, shock and brake drum etc. Moved on to the other side and the spring plate won't slide onto the splined bit of the torsion arm at all. It's almost as if the torsion bar is ever so slightly too wide. I count 52 splines on both the torsion bar and spring plate. I see on Schofields that there is an early and late spring plate. What's the difference and could this be my issue? I.e one of each on my bus?!