Valencia 846U - what does the U signify?

[Bobg100]

I just found a mint pair of 846U Valencia. When I try to research them, I keep seeing 846 A and B.
What is the difference between the A, B and U? Are the U worth less? thank you.

 

[bowtie427ss]

Unfinished version of 846B.

846A 16 ohm, earliest version

846B/U 8 ohm, removable motorboard

 

[Mr Boochie]

I just found a mint pair of 846U Valencia. When I try to research them, I keep seeing 846 A and B.
What is the difference between the A, B and U? Are the U worth less? thank you.

U = just right for U!

 

[OBMG74]

Nice find, great with tubes!