I have no idea what kind of clutch material it is. I bought the kit mentioned earlier and just installed it. I didn't replace the solenoid pack or the torque converter. I was getting noise in the transfer shaft and it was slipping from second to third so I didn't bother with those.

The clunk is only when shifting into to either forward or reverse from a full stop. It's like the sort of thing you'd expect if your universal joint was shot in a rear wheel drive. Otherwise it shifts very smoothly. It could just be me being hyper-sensitive to everything since it was just rebuilt but it seems odd that it doesn't do it every time.