I don't think there are any manufacturers doing drivers like the 515B. 416, 9449 etc. The construction quality, size of the Alnico magnet etc are not done these days at all.
Reconed vintage drivers are are better than the new stamped woofer basket, ferrite magnet stuff peddled these days.
There is a misconception regarding this debate why present day drivers are not like the vintage 416's or 515 . We see all this thru an user's end eyes or something we would like to see around but that isn't. As though vintage lovers have a desire for these drivers and have an opinion that such drivers should be produced in the present day also . The reality & fact is that commercial it is not a good idea to produce a big daddy 15" driver with a power handling of only 20- 30 watts.
No big manufacturer will be interested to produce them seeing a very very small market globally.
Regarding build quality and budget drivers. Here also cheap stuff or budget driver are catered for a different market which is very big and does well in commercial sense.
You cannot draw a conclusion on the entire industry on this line. In early days the hi end top drivers were certainly the old Altec's , University, Goodman's ...... They were the superior drives of those days which were build to the ultimate quality of parts and technology available at that time.
Presently the top end drivers are technically & sonically much ahead and superior in comparison to vintage drivers. Many things have changed since then. Lots of development had been done in fabrication of Frames , magnet materials and motors parts & optimization of magnetic field geometry of motor structures in terms of attaining symmetrical gap field, lower distortion, temperature reduction to over come non linearity and compression. Voice coil material and wire had too seen similar changes. Soft parts as cones, surround suspensions, spiders, diaphragms material and their geometries are now different and are much much ahead and superior to the old day drivers.
Early day drivers had all these limitations in terms of technical advancement & development since these were discovered as years passed by through extensive research and development in many fields.
In present day if any manufacturer ventures in manufacturing drivers similar to 416 or 515, it is quite possibly and would be more superior to the earlier ones with the addition of the current technology and superior parts quality.
One may also argue over keeping all aspects aside and compare side by side a vintage 416 vs present day 15 inch in terms of tonal or sonic quality. Then comparison should be fair enough by having the modern 15" driver with the same power handling capacity as the 416.
Unfortunately there is no such driver out there. Except for the GPA version of the Altec's built to the same specs.
Vivek