I recently got a great deal on an ebay auction for a small batch of chatham 5998s. However they are quite differently constructed compared with the chatham 5998s that I already have in my amp. The ones from ebay have clear top ends, double bottom D getters, grey plates and “pigtail” filament wiring. The ones I have in my amp have smoked glass on top, top getters, straight wiring and black domino plates with a “brushed” look compared with the “grainy” grey plates in the ebay batch.
So, is my understanding correct that, despite the ebay batch looking identical internally to a WE 421A, they are still regular 5998s and that the only differences to the chatham 5998s in my amp are that they are an early construction and that they are not from a military stock (given the absence of JAN markings)?
Sound wise the two versions sound very very close with the ones I already owned maybe a tad more full bodied and warm, but this could be due to them being burned in after two years of ownership.
Adding images below with both the version from the ebay batch and the one in my amp.
Thanks!