I have an 81 Toyo Pickup used strictly offroad. I have a small leak in the left rear brake line where the line curves around the axle by the slave cylinder. This line is one piece steel tubing from the equalizing block to the slave cylinder. What's the best way to repair this. I've looked for a steel replacement, but can't find anything other than a 18 to 20" hyd hose. Thanks ahead of time.

Repairing a brake line isn't good, it should be replaced.
You can buy pre-made lines with fittings installed and bend it yourself, or a piece of line and install your old fittings if you can rent/borrow a flaring tool.