Where can I find suitable tubes for OTL projects and OTL power amplifiers?

For OTL projects and transformerless tube power amplifiers, powerful and proven tube types are especially sought after. These include 6336, 6C33C-B, EL509, EL519, 6C41C and 6080 / 6082. Especially 6080 / 6AS7G are considered classic OTL tubes; Atma-Sphere explicitly describes the 6AS7G as a particularly suitable type for OTL amplifiers. 6C33C-B and 6C41C have also been well-known power tubes in the OTL field for years, while EL509 and EL519 repeatedly appear in special OTL and high-current concepts. Anyone who wants to replace defective tubes or build a new OTL project should therefore look for suitable types for the exact circuit and load.