6CA7/EL34 quad of XF2 brown-base tubes Tung-Sol, RCA

I got these from a fellow Audiogonner who told me they are most likely from Vintage Tube Services. Obviously they are old-stock tubes; one is marked Tung-Sol, one RCA, and two are unmarked. All are marked XF2 on the glass. The tubes are all identical construction, dark brown base with double getters at the top. The date codes on the tubes are B6J3, B5J4, B6H5, and B4F9. I used them briefly in a tube amp I no longer have, but I don't have a tube tester and have no way of testing them other than to say that when I used them last (about two years ago) they sounded fine (I did not listen to them critically at the time). I used a less-rare set of EL34s in my amp and sold those with it. These have just been sitting around in my closet ever since. I know they are high-quality tubes but I do not know the exact vintage or lineage. If there are any questions, please feel free to email me. I will pack them safely to ensure they arrive unharmed (check my feedback, I am not new to shipping tubes). Buyer pays shipping. Please email with any questions. Thanks.