The 5R4WGB tube is a industrial version of the 5R4 tube. It has a huge silicon filled base and extra thick glass to greatly reduce vibration. Replaces any 5R4 tube, but make sure it will physically fit into your application. Seated it measures 4 5/8" tall by 2 1/16" wide.
Various brands in stock. Most are Raytheon, Chatham, or Cetron.