The SN74LS158N: This is a standard-production 74LS logic part, not a shortage-era allocation item, so the supply chain is predictable for both new builds and legacy BOM support.
The SN74LS158N is a 4 x 2:1 multiplexer from the 74LS Schottky-clamped bipolar logic family. It selects one of two 4-bit data sources onto a single 4-bit output bus — the same function as the '157 but with inverted outputs, which simplifies certain bus-multiplexing topologies. Output drive capability is 400 µA sourcing and 8 mA sinking — enough to fan out to ten 74LS loads but not to drive a 50-ohm backplane directly.
The supplier device package is 16-PDIP. No fine-pitch or BGA concerns — this is a standard breadboard-friendly footprint that routes easily on a two-layer board. Shipped in tube packaging. The 74LS series is 5 V TTL-compatible; no level translation needed when interfacing to other 5 V logic families.
The date-code and marking trace back to TI's authorized chain; no gray-market concerns for an active, widely stocked part.