Replaced pilot assembly, valve tube sheared

It is a soft (annealed) aluminum tube with compression ferrules. Measure the OD of the tubing, then take a look at mcmaster carr if you can find compression sleeves that look like yours on McMastercarr.com.

Most modern appliances use a flexible stainless steel pipe to make this connection. The flexible hose can easily be found in the plumbing section of your local hardware store. They will also have NPT to flare brass fittings to make the connection on the valve side of the system.

To connect the stainless pipe to the jet is going to need the brass fitting, which is usually a 90 degree with NPT threads onto the jet. Remove the entire jet by wrenching on the 90 degree connector, the parallel threads into the burn tube will usually not be as tight as the NPT threads between the bottom of the jet and the 90 degree elbow. Then go and look for a replacement elbow with threads that match the jet on one side and a flare cone on the opposite side to match the flexible hose.

It just occurred to me that the jet is always a straight fitting with an brass elbow screwed onto it, so all you need to change is the elbow and not the jet itself.