My spreaders are aluminum, 1" O.D., 35.5" long (without the plastic end caps).  I measured the wall thickness at 0.075", but there are some burrs on the inside, so the true thickness is probably less than that.

I've never attempted to communicate with anyone from Dwyer, but I've ordered parts from their website without any problem.

I didn't find any premade spreaders the right length, but you can buy marine grade aluminum tubing by the foot and inch.   They list 1" O.D. tubing with a wall thickness of 0.065" for $12.74 per foot.  The part number is 'RT 1000'.

HTH,

Peter Nyberg
Coventry, CT
s/v Silverheels (1988/2016)