4,500 dollars for a 8 & 3/4 .....?

Had anyone heard of a Mickey Thompson rear end (peg) for 8 3/4 ? Fellow up my ways has one for sale and claims they used to use them back in the day on dragster. Because of the night H.P and weight of the Dana these were preferred, @ 60% weight loss, they were fur best thing. It actually had a front section that allowed you to tie it also on to the chassis.
Anyhow, my question is, does anyone know of these and are they worth it ?
Thanks.
MAPS