I went to rigrite and they wanted $189 each for the spreaders.  Dwyer mast has an off the shelf spreader you can buy for $62.  I will let you all know how well it works when I receive it.

The dimensions of the spreaders on my boat are as follows:

OD  1 1/2 inches
Wall thickness 0.075
ID 1 3/8 inches (actually 1.370 according to my micrometer)
Spreader bar length 32 inches
Length to shroud seat 32 1/2 inches
There are 2 1/4 inch holes 1 inch from the mast end of the shroud, aligned parallel to the mast

The dwyer spreaders are thicker than the ones I am replacing, with a wall thickness of .125.  This is also true of the spreaders that rigrite makes.  You can order thinner tubing and make up the spreader yourself with parts from rigrite, though.

I bought two spreaders from Dwyer for $62 each.  I like the tips on them because they have a metal tab that goes across the shroud opening to keep the shrouds in the slots.  I am very pleased with the outcome, though the wall thickness of the new spreaders is greater than the old ones so they are a bit heavier.

I will post pictures when I launch the boat.