I answered this earlier this afternoon but evidently it didn't stick around.
Yes I think these wheels came at the same time as front disc brakes in 1971. I bought mu '70 Blazer new but the dealership had added 16.5 wheels. It has drum brakes but it has been a long time since I had a front wheel off to see if it has the 3 rivets. It has the same drums as my '53 pickup.

"I wonder if God created man because he was disappointed in the monkey?" Mark Twain