Your honest opinion

I have a B-Body 8.75 rear end (I think its a year '71-'75) complete drum to drum with a open 3.23 and 489 case that I bought with the intention of narrowing and dropping under my A-body but I have decided to go another route. I put the rear end up for sale for the same price that I got it for...$600 and I got into a conversation with a guy that was interested in trading for it. He offered up a few different things but what caught my eye was his 8.25 he said came from under a '70 Duster with unknown gears and open center. I asked him to put some cash on top on his end and we have a deal and he seemed to get offended and blocked me.
I can admit when I am wrong but there is no way that these two rear ends are worth the same... are they?
What would you honestly say both rear ends are worth?