Mopar Madness rear axles??

I've used Cass for parts sourcing as I do my own building. In terms of cost - IMO $2600 for a "489" with a crush collar, True Trac, and restored drum brakes is a little strong money for an 8 3/4.
If they had to buy a core A body 8 3/4 and go through it that's fair. But the ad leads me to think they will cut and shorten a cheap case and fill it for that figure. As an example I get about $1200 plus shipping for a "489" chuck with any gear, Tru Trac, everything new but the case and yoke, and the billet spacer. (they want another $100 for for a $40 part there). That's me supplying the "489" core.
It's always buyer beware. I've seen several of these types of vendors popping up and until they get some good feedback it will be a crapshoot. Teh big problem with gears is if the setup is not good there's a very good chance that the new gears will never be quiet, adn once it's in and the "rebuilt clutch type grip" (or worse a "rebuilt" cone type) begins to slip after 100 miles and a couple strip outings it all has to come apart again anyway. So my advice is go with reputation if you indeed only have the ability to "do it once". I've also had to repair units that have were sold as "rebuilt" that were painted and had a new gear set with a new inner pinion and race...