There seems to be real questions on what the ID of this watch is based on conflicting ads and the similarity to the AA "ZZ". I have a theory I'd like to put out there. After examination of basically all HE LL , HE "no variant" in this style and AA ZZ models on the site, I see some interesting patterns. First, it appears that the 2 models are in identical cases with different faces and crystals being the distinction between the two..
1949 AA had a gold back and LL had a stainless back (per one ad). The earliest AA ZZ on the site has a serial number starting with a 4, as does this watch and a couple of this style listed as HE no variant with gold backs
One 1949 ad shows this as a HE with a gold back and bracelet, while another from the same year lists watch with a stainless back and leather band as an LL.
Serial numbers of AA ZZ progress from starting with a 4 and increase to 8's as time passes.
Excellencys in the LL style seem to start at 8 and go up from there (with gold backs). There doesn't seem to be any proof that this model with a stainless back exists except the ad. One would think that if there were SS back examples out there, one would have made it's way onto mybulova by now.
There also doesn't seem to be any confirmation of 14K plate as the one 49 ad states, only 10K examples. I think that was a misprint.
Is it possible that because the AA ZZ and HE LL were released at the same time, that parts were interchanged at the factory in 1950 and 51 perhaps in response to the AA lawsuit? Build the ones first that aren't in jeopardy of being in question.
It's possible that cases and backs destined to be AA's were sent to be assembled as HE LL's. The apparent discord in serial numbers would say it's likely. Unless there is a documented HE LL out there with a stainless back, it's my humble opinion that any watch in this case irregardless of back color with a one color face is a HE LL and any with a X Shadow face and with or without a faceted crystal covering it is an AA ZZ.