I need to replace my entire front yard system with a new layoutbut unable to afford it right now. What I do need now is to replace the gear driven heads I have. The problem is that they are a circular pattern and the the only ones I can find are single stream. The single stream will not work with my current lay out. The ones I have were made by Rain Jet and probably installed back in the 70's, any ideas on where I should look? nw1954