Cut off two pieces of the smaller steel channel to the appropriate length for the upper frame mounting bracket. Cut off two pieces of the 3/16” X 1” flat steel to the appropriate length. Drill four holes in each piece and bend at 90 degrees as shown. The two holes in the short leg will be used to puddle weld it to the steel channel, not for bolts. Cut the ¾’ square tubing into two pieces, about 2 feet long each. Using the bent bracket as a guide, mark and drill the holes for the bolts in the square tubing.

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Weld the bent brackets to the steel channel and grind off the rough spots. As you can see, I did a lot of grinding since my welding is not so good. At this point you might want to paint the upper frame mount brackets and down tubes.