8-3/4 question

Did Ma Mopar use the 8-3/4 in a 73 340 Duster. I've read in a couple places that the 8-3/4 was only used until 72 then in 73 they went to the 8-1/4 even in 340 cars. But it's been quite awhile since I read that and can't find it. I did find this link on Moparts that vaguely the 8-3/4 was used up until 72 and the 8-1/4 was 73 and up.

http://www.moparts.org/Tech/Archive/axle/6.html

Reason I ask is I saw some on E-bay and the have the big bolt pattern. I can't afford Yukon's so I thought at least these would be an upgrade to the big pattern and 1/2" studs. When I politely asked the seller if they were for sure 8-3/4 axles for an A-body with the big bolt pattern because I read they only used the 8-3/4 until 72 and then went to the 8-1/4 even in 340 cars he got extremely rude and this is the e-mail I got from him.

Look here. They are 4 1/2 in. bolt pattern axles out of my 8 3/4 rearend. NO INSPECTION PLATE. CHUNK REMOVES FROM FRONT. I have been dealing in MOPARS for 40 yrs now. EVERY 1973 340 DUSTER CAME OUT WITH AN 8 3/4 REAREND. DONT QUESTION MY INTELLIGENCE.

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Well I promptly let him know he didn't have to worry about answering any more questions from me as I wouldn't be bidding on his axles.

What do you all think? Did they in fact use a 8-3/4 in 73.

Anybody know? Thanks, Tracy