I went with a company that sells splined shafts and sleeves and made by own long slip shaft. Find a tube that fits one their sleeves and order the splined shaft to match. Then get to welding. I ordered two sleeves and spaced them out about 3/8" and tapped that space with a grease fitting. Never wallowed out and became sloppy. Still using it today on my linked rig.
http://www.grobinc.com/broached-sleeves-and-flanged-bushings/
