I have a couple of Titan 57 saws and one Double Eagle 50 put together, enough parts to make up a Titan 50 as well. As noted above, the fuel and oil lines were made from whale snot or some other junk and will always need to be replaces and the coils are prone to failure, but the same coil was used on a few other saws, I just can't remember which. Same goes for the plastic mac saws like the 32-38 cc models, same coil was used on a number of string trimmers.
Never let a coil failure cause you to believe a saw is gone forever or that you have no other options. Many times you can find a similar coil on another piece of equipment and remove the coil and install it on the original laminations to make it work. I'd have to do some digging but Ike Holts on another site was showing one (Husky 50??) that could be repurposed to 10 Series and SP105/125 saws.
You might spoil one or two in the process, but you will never know until you try.
Mark