Here's the GE version, it looks like the lamp in the 6th picture might have lost vacuum?  https://www.ebay.com/itm/222720943316?   "GE 18783 WL 95/120 120V ELECTRONIC BALLAST & GE 18836 95W HPS WHITE LUCALOX LAMP"

Here's some /DX lamps, it looks like they have pictures of 2 different lamps? https://www.ebay.com/itm/175351731379?  "LOT OF 6 CEW LU150/DX/MED 18094 High Pressure Sodium Lamps"

VINTAGE NEW OLD STOCK - 4 EYE IWASAKI DAYLUX NHT50SDX BULBS IN ORIGINAL BOX. https://www.ebay.com/itm/155734078586? These seam to work okayish on a standard 50w hps ballast.

I also got a bunch of results searching for "sdw-t" but I couldn't find a matching lamp and ballast for a reasonable price.

RRK: I have seen similar difference. The magnetic SDW-T colour is looking like "more fresh" than electronic SDW-TG.

In this video featuring Japanese high pressure sodium lamps, I see that the K-HICA lamps from National/Panasonic and Iwasaki’s “DX” lamps seem to operate properly on special magnetic ballasts and they have a CRI of 85.

See here:

https://youtu.be/Y3Dvdn2fXX0?si=HDG_6gmkgl0sBCJh

need video wish I could understand Japanese
looks like he has 2 self ballasted HPS lamps

From what I can tell, these high pressure sodium lamps with the incandescent filaments still require external ballasts and they only use the filaments to aid in starting the lamps.

If you look at the 20:24 timestamp, you can see an external ballast connected to one of the lamps with the filaments.

looks that way in the vid as the ballast gear is still there and they don't show doing anything between bulbs
maybe "starter-less" so they can run on MV gear?
interesting bulb anyways

You are right in that the Iwasaki NH270L/N, NH270FLS, and NH270FL high pressure sodium lamps are specifically designed as retrofits for Japan’s 300W mercury vapor lamps, but the Iwasaki NH400DX and NH400FDX high pressure sodium lamps are electrically different from most 400W mercury vapor lamps in the world in that they all have an operating current of roughly 4.7A and an arc voltage drop of roughly 100V while most 400W mercury vapor lamps in the world have an operating current of 3.25A and an arc voltage drop of about 135V. Interestingly, the Panasonic K-HICA 400W high pressure sodium lamps have an operating current of about 4.9A.

Here are the specs for the Iwasaki NH400DX and NH400FDX high pressure sodium lamps:

https://www.iwasaki.co.jp/lighting/support/products/detail.php?ItemNo=NH400DX

https://www.iwasaki.co.jp/lighting/support/products/detail.php?ItemNo=NH400FDX


Here are the specs for the Panasonic K-HICA 400W high pressure sodium lamps:

https://www2.panasonic.biz/scvb/a2A/opnItemDetail?use_obligation=scva&contents_view_flg=1&catalog_view_flg=1&item_cd=KHICA400GN&item_no=KHICA400GN&b_cd=101&hinban_kbn=1&s_hinban_key=KHICA400GN&s_end_flg=&vcata_flg=1


Another thing to note when looking at this Japanese lighting video and Japanese lighting documents is that you should download the Google Translate app on your smartphone and you can translate the Japanese text into English by taking screenshots of the Japanese text and having the Google Translate app translate the text into English just for you. That is how I translate the Japanese lighting documents that I found into English so that I can get a decent understanding about Japanese lighting documents.