Funny, the model 140 is listed in the early '60s catalogs as a 6 lug drum, but the photo shows 8. Then, in the later '60s catalogs, they say it's 8 lugs, still the same photo.
Those are the ones with the "crinkle" type aluminum shell, not ribbed like yours.
I've seen the crinkle ones in 6 lug, but don't remember 8 lug ones. The ribbed ones I've seen were all 10 lugs but I don't see them in the catalogs. I'm just looking at the catalogs on the web site; maybe the 10 lug ones are shown in the student snare kits section??