Want to buy: STRATE-CUT Model 3551 UNIVERSAL CUTTING GUIDE sold late '60s early '70s by R.A.K. PRODUCTS, INC P.O. BOX 23426 MILWAUKEE, WISCONSIN 53223
They consisted of 2 - approx 50 inch x 3 1/2 inch extruded aluminum straightedges with a coupler.
They don't seem to be in business anymore. I lost one of my set.