The subject tubes are PCC88/7DJ8 dual triodes from the Tesla Rožnov n.p. Závod Vrchlabí plant and were produced in 1965 (the six used in the Premier 16LS2) and 1966 (the single tube used as input for the Premier 140), in what was then Czechoslovakia.  They were purchased from the online vendor Tube Monger at a cost of $50 per pair.  According to Tube Monger, these are supposed to be superior to later production PCC88 with the 37 factory code from the Trinec plant.

The Tesla PCC88 replaced Telefunken (manufactured by Siemens) PCC88 tubes in both the Premier 16LS2 and 140.  Output tubes were 1960 vintage Tung-Sol 6550 black plates with triple getter construction (see this review of the earliest production top-getter only Tung-Sol 6550 black plate) and Sovtek 6H30π-DR phase splitters in the Premier 140.

Tesla PCC88 Line-Up                                                                            Tesla PCC88 Front View
     

Tesla PCC88 Rear View                                                                         Tesla PCC88 Close-Up
     

Tesla PCC88 Thick Getter Ring
    

Listening Impressions:

• Frequency response is evenly balanced and leans more to the German side (Siemens and Telefunken) of the spectrum than the Dutch (Philips/Amperex).
• Bass is solid but never draws undue attention to itself.
• Midrange is clear if a little lean making dialogue easy to understand.
• Detail is excellent with a crisp transient response.
• Upper treble is extended and airy.
• Dynamics are top-notch and the overall presentation is quick, peppy, and sparkly.
• Not as grainless as the best (Amperex, Telefunken and Siemens).
• Soundstage is wide, well-layered and populated with larger, slightly more diffuse images.
• When the recording allows, such as Vivaldi’s L'estro Armonico, Op. 3, Vol. 1: Concertos No. 1-6  DVD-A, the venue’s ambience is nicely captured.

Overall, I find the Tesla PCC88 an excellent performer and would make an especially good choice if your system tends to be a little on the dark side.