I've got two 1210's. Which one should I upgrade?

A
GE0LX001111
SL-1210mk2-A
RGN0930-K1

or

B
GE2EY001350
SL-1210mk2
RGN0930-K2


I bought A in 2008, I'm guessing it is October 2000.
I bought B in 2010, so May 2002.

I haven't seen anything with the 1210MK2-A what's that about?
At least they were both before the high capacitance era.

Finally, I've bought a 21V linear power supply. Can someone post a picture of how they've connected theirs to the deck? Have you put a DC input plate, or done something with a cord? Any tips on someone that could do that in London would be greatly appreciated.

R