Pretty much all of the 50s Fender tweed amps were 6V6 with a few 6L6 in there too. However, the only current tweed amps based on those old 50s models are 6L6 in the Blues Deluxe and Blues Deville or the EL84s in the Blues Jr which was an odd choice IMO. I know most of the Reverb re-issues have the 6V6s but why no tweed amps with them? I really wish Fender would make some 50s era tweed re-issues with 6V6s. The originals are some of the most sought after amps of all time, I'd imagine re-issues would be quite popular. Its long overdue.
The modern 'tweed' amps don't really have a lot to do with the 1950s tweeds at all. They are designed to sound more like the 1960s blackface amps than the 1950s tweeds.
The tweed amps of the 1940s and the first half of the 1950s sounded quite different. Generalizing here, the tweeds:
* were cathode biased, giving more compression and less efficiency;
* were equalised to pump out more low mids;
* were more primitive in their power supply, causing 'sag'; and
* gave less clean headroom.
All of that made the tweeds fat sounding, and prone to a really growling kind of overdive when pushed hard.
So for example, the 1950s tweed Deluxe had a pair of cathode biased 6V6s, powered by a primitive power supply with poor voltage regulation and no current regulation at all. They were driven by a cathodyne phase inverter which was prone to blocking distortion. It had two channels (bright and normal), with independent volume controls (that actually interact in interesting and unintended ways), and a single master tone. It was about 13-15 Watts into a 12" speaker. It was nothing at all like the modern Hotrod Deluxe or Blues Deluxe.
(BTW, Fender does a custom shop hand wired reissue of this amp, and there are hundreds of clones out there.)
In contrast, the blackface amps had stiffer power supplies and higher voltages. This gave them better dynamic range and extended treble response. They were equalized to cut a lot of low mids, but produce lots of treble. When that combined with extra power and treble it produced the 'sparkling' clean sound that Fender is now famous for. The modern amps are designed more like the blackface amps than the tweeds. The exception there might be the Hotrod Pro Junior. The rest are pretty much blackface voiced amps with overdrive built in.
So the modern 'tweeds' are really only 'tweed' amps to the extent that they're covered in tweed.
