Is this a stock CL350 K4 tail light?

So the big bright red thing at the back of my bike went dark the other day... on inspection the wiring lead that connects to the back of the reflector has broken off and I need a replacement unit.

I checked the parts manual for my K4 cl350, and the number 33703-077-671 turned up. I went on fleaBay and found a nice NOS unit, had it shipped, and when it arrived I was surprised to find that it is a great deal smaller than the "what I thought was STOCK" light. The ebay ad stated CL350 as a recipient, and its overall look is very similar, it just seems somewhat shrunken in stature? Also the mounting holes are narrower than the original mounting holes, so either the reflector is from a smaller bike, or my entire tail light assembly is from a bigger bike?

Since I run a stock luggage rack all the time, I like the way the large OEM unit fills the space.... can anyone possibly tell me what is going on here? Am I currently running a stocker light from a different Honda bike, or am I confused on which part number is supposed to be used on a 73 CL350 K4? The back of the reflector on the bike reads "STANLEY HM-16RC", the back of the Honda part 33703-077-671 reads "STANLEY IIRC" with the letters YH05 stamped to the upper right.

Any help is much appreciated. Pictures below.

DOT dick-tated the size of the units, bigger as years went on
i use cycle chaos many times to identify stuff, it is not always 100% accurate but usually has lots of pitchurs of different makes/models
check it :

http://www.cyclechaos.com/wiki/Honda_CL350

Yeah, that info is from CMSNL, which I find is occasionally wrong as in today's case... and I think the new one might read HM-11RC instead of HM-IIRC

The smaller light is for a K1-K2. I prefer it over the larger, later version.