Interestingly, here is a comparison of spec sheets of electrically interchangeable Iwasaki lamps compared to the base mercury vapor lamps:

400W mercury vapor:

https://www.iwasaki.co.jp/data/discon/HF400X/10/0001890.pdf

360W high pressure sodium retrofit with thermal starter:

https://www.iwasaki.co.jp/data/discon/NH360L/10/LN410351B.pdf

360W deluxe high pressure sodium retrofit with thermal starter:

https://www.iwasaki.co.jp/data/discon/NH360DL/10/LN410393B.pdf

360W high pressure sodium retrofit with FEC ignitor:

https://www.iwasaki.co.jp/data/NH360LS/10/0000884-2.pdf

400W quartz metal halide retrofit with glowbottle starter:

https://www.iwasaki.co.jp/data/discon/M400LE_BUP/10/L430003A.pdf

400W quartz metal halide retrofit with FEC ignitor:

https://www.iwasaki.co.jp/data/M400LSH_U/10/0000816.pdf

400W high CRI daylight quartz metal halide retrofit with glowbottle starter:

https://www.iwasaki.co.jp/data/M400DL_BUDP/10/L430075.pdf

360W ceramic metal halide retrofit with FEC ignitor:

https://www.iwasaki.co.jp/data/M360CELSP-W_BUD/10/GL09P10-2.pdf

https://www.iwasaki.co.jp/data/discon/M360CELS-W_BUD/10/0001669-2.pdf

https://www.iwasaki.co.jp/data/discon/M360CELSH-W_BUD/10/KLS410030-1.pdf

Hmm?, problem is, adapting every HID type into what are effectively multi vapour lamps must have an effect on life and efficiency?
Having separate lamps and gear means you can specifically concentrate on making ‘that’ lamp technology the best it can be?
Something that confuses me though, as the primary inventor of the LED filament lamp it makes me wonder why the Japanese are still producing discharge lighting at all?

Cfl didn't retrofit much in India but led sure did. Even before led tubes existed, led battens that could be independently placed or inside a fixture.

I think I may have two. What would you like to pay for a genuine 50w MV ballast?

I sent another seller of some 26w PL-C ballasts an offer. If they decline, I'll definitely consider it. I would definitely like a real 50w MV ballast because it would be a cool thing to have in the collection.

I might be interested in a few.

I'm pretty sure it's an Advance 71A1800, which is HX autotransformer, but I need to find it.

Btw, both 50w Advance mercury CWA and HX ballasts can be seen here next to each other.

For example, here is an example of a Japanese 400W mercury vapor ballast that is still being made:

https://www.iwasaki.co.jp/lighting/support/products/detail.php?ItemNo=H4TC1A51

In Japan, I still see the mercury vapor ballasts still being produced, but only the lamps have been banned.

@ HID Lad, more than likely, and with all new installations of MV banned, it's the only logical thing for them to do. 

@ WWHID, they banned them because they could... 

I am also wondering why the selection of self starting mercury vapor retrofit lamps in other countries was more limited like in the USA or the EU countries and why the EU decided to ban high pressure sodium retrofit lamps.