[TR] Trunnions later TR4 with 3 degree caster

[Randall]

> So it doesn't hurt the trunions to crank them a couple 
> degrees out of shape, 
> then. 

No, I didn't say that.  The late TR4 took different trunnions than the
TR2-early TR4; and being a "couple degrees out of shape" is the only
difference between the three different trunnions (0 degree both sides, 3
degree right and 3 degree left).  It is apparently possible to assemble them
that way, but unless things are badly worn, the result will be binding.

Randall