The Panda is the 6138 that translates without explanation: a silver dial, two black registers, the layout that Swiss chronographs made famous and Seiko made affordable. It is widely regarded as the 6138 to reach for first, the family's cleanest design and its most liquid reference on the secondary market.
Popularity has its tax: panda dials are the most redialed in the family, because the white-and-black scheme shows age honestly and a refinished dial photographs like a new watch. The originals age with even patina and correct printing; the redials are brighter, flatter, and everywhere.
The gateway 6138 and the one where dial originality is the entire price. A worn original Panda is a better watch than a gleaming redial at any price difference, and the difference between them is learnable in an evening of studying certified examples. Spend the evening.
Production windows and specifications compiled from documented collector references and period catalogs, cross-checked across independent sources; manufacturer records for this era are approximate by Seiko's own account.