I'm working on a system that is probably about 15 years old or so. The entire system was Toro at one time, but through the years, vavles, heads, etc. have been switched to Rain Bird. There is also some pretty funky piping going on, especially at the main manifold. I'd like to save myself some digging, root pruning, and complicated re-piping by replacing the guts of this one bad valve with a new one. There is only one set of numbers etched on the valve..."L88". This may be a shot in the dark, but does anyone know what I'm dealing with?