Both the CRT's for the 5154 and 5153 were fairly unique. (I think the one for the 5154 is easier to get).
I investigated this for the 5153 VDU and I bought a "near equivalent" CRT as a spare for my 5153, the only difference it had, with respect to the original, the original had very dark faceplate glass (it helps improve the contrast because reflected light has to pass twice the face thickness to be reflected off the phosphor) the equivalent CRT I found had clear or very light grey glass.
One thing that makes both of these color CRT's very "special" is the particularly fine phosphor dot pitch. It is this and the shadow mask that sets the ultimate video resolution, not the bandwidth of the video amplifers, they are more than adequate. For example I found out when I modified a 5153 VDU to display an EGA image, that the video amplifiers were fine for the task. It may be possible to use the 5153 CRT in the 5154, I have not investigated if that would be ok, or not.
There is an ebay seller who is in Canada. They are called Newtubes, and have large stocks of generic CRT's, but they have something else, a master list of potential CRT equivalents and if you gave them the number from the CRT in the 5154, they would advise what a replacement part number could be, and if they have one in stock.
Also, if you want a new CRT, look to see if Richardson Electronics in the USA still has your original part number in stock.
You may or may not be aware of the World's status with the CRT. No company has been able to repair or re-build a CRT for more than the last decade. Nobody is currently making any except for some military vintage radar support applications but I think they are now gone too. Every CRT now is a "non-renewable resource" and good working CRT's, especially new old stock ones, are more precious than the Jewel on Romancing the Stone, because, not only are they things of beauty, but they do something useful.
The CRT in its final form, represented a pinnacle of achievements in multiple fields, electron optics, metallurgy, glass work, metal glass seals, cathode coating and phosphor technology (which in itself is a science) and the integration off all that into manufacturing techniques which took many decades to iron out the bugs. You won't see another CRT factory reappear, many of the Engineers of that era are retired and a lot of the skill and knowledge base goes too. CRT's have gone "Bronze Age". I think you couldn't make a proper color CRT or a scope CRT (like the ones used in the Tek 2465B, a jaw dropping masterpiece of electron optics) with the required precision unless you had about 10 Million $ or more to spend and nobody is going to do it, because flat panels have taken over (for better or worse)
