Tranny Tubes [upd] -

In older radio equipment and high-end audio gear, transformers ("trannies") and vacuum tubes are sometimes housed next to each other inside protective metal cylindrical covers or "tubes."

In the automotive world, "tranny" is a common shorthand for the transmission. The "tubes" generally refer to two specific components: tranny tubes

: Lightweight, rust-resistant, but more prone to bending. In older radio equipment and high-end audio gear,