Rear end squatting

Hello! I’m restoring a 98 grizzly 600. This thing has taken a lot of abuse. I took it down the road on the pavement and as soon as I hit the hardtop the rear sunk severely. I put it in 4wheel drive and it sunk even worse. I took it out of four wheel drive and had to get off and pull the ass end of the 4wheeler back up. I don’t know if the rear shock is toast or if something is binding up somewhere. It does it in soft and hard positions. Has anyone else experienced this? Thanks for any replies!