Flex disc? The Rubber Guibo between the tranny output and the drive shaft?
$79.00 at bavarina Auto but should be widely available. I believe I've read the exhaust needs to be disconnected soemwhere maybe at the ex.manifolds to allow the driveshaft to be dropped enough to R & R the Part in question so doing it In Situ is probably a no go. Tow it to the nearest garage with a lift. That's my guess.