Is it necessary to replace the crown wheel bolts on 8-3/4 ?

70Hardtop said
Thanks for advice - but I cannot work out what TTY is? Something to do with torque values? Are head bolts and main cap bolts TTY? As I said in another reply, in Aust I will have to pay between $56 (OEM) and $76(ARP) for them. So not exactly cheap.

TTY=Torque to yield. Don't mean to be confusing, all TTY bolts must be replaced, non TTY do not.