[Elecraft] K1 build issue

[bud73 at comcast.net]

I am close to finishing building a K1 and am presently about to install the two T-220 power transistors, Q6 and Q7.
The K1 assembly instructions indicate that Q6 (transmit driver) is a 2SC2166 and is labeled C-2166.  My T-220 package is labeled C-5739.  Is it OK to use the transistor that came with my kit?  Are they electrically the same?
Also, according to the instructions (pg. 43), I am suppose to mount a "self-adhesive thermal pad" under Q6 and Q7.
I did not receive any thermal pads with my kit.  As Q6 is a plastic T-220 package, I don't understand why I need a thermal pad under it.  Thanks in advance for any help/suggestions.

Bud,
NY1Z