1987 Ford econoline grind problem?

IT IS YOUR UNIVERSAL JOINT some don't have grease zerts and some do but are sealed you can't grease them but know matter the case replace them a rear wheel drive has 2 of them you have the front universal in which it located right behind the transmission and the rear right ahead of the rear end usually its the rear that wheres out sooner because it does the most flexing between the body and the rear axel there is a nack to installing them that most machanics don't obide by make sure your machanic equalizes them when replacing it you have to give them a sharp rap with a hammer on both sides anyway they turn on needle bearings and if ignore them bearings turn to dust and your drive shaft will fall out most generally starting out from a stop sign thats when they are under the most stress or going up a hill get them checked out once they start wearing out water will the seals and dry out even quicker good luck