Roy,

It's dark and raining now or I'd go look, but if memory serves the 1800 coupler is about 3/4" thick rubber. There are hex-drive cap screws with heads down in the rubber in metal sleeves, two fore-aft, two 90 degrees out aft-fore, threads sticking out. Nuts and washers secure these to yokes clamped onto the splined steering shafts on both sides. On mine, the spacing of the shafts is such that the bushing is under slight tension -- it's pulling the shafts together, not keeping them apart -- but there is very little distortion of the rubber.

The earlier-style 122 coupling is only 1/4" thick, and is a rubber/fiber material that looks like it's made of old door mats. Regular bolts go through it, bolt heads contacting the yokes through washers. The bolts are spaced slightly wider apart -- you couldn't interchange yokes and couplers from one system to the other.

There's enough play in the three bolt holes that hold the steering box on for some vertical angular adjustment to be possible, but not enough to move the whole box significantly in the horizontal axis. I haven't played around enough to see if the steering wheel and that end of the shaft is adjustable in that direction.

Hope this helps,

--Phil