In addition to the occasional OEM 2L Banana by Bischoff or Leistritz on here & the other usual classified sources for used & NOS parts, Dansk makes the current OES replacement 2L Banana & it's sold at most of the usual sources, so try GPR, Pelican, Automation, TCsGarage, SMC, AA, etc. & see who will give you the best price. Porsche dealers may also sell the Dansk, & then you can use the PCA 20% off discount whenever one is available for your local dealer.
Pic of Dansk 2L Banana:
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