i know this a gmc forum but my uncle told me was hearing a odd noise coming from the rear of his truck so i looked under the rear of the truck and it was dripping fluid from the rear cap seal is there a easy way to fix this he can't do the work himself due to having open heart surgery back a few months ago so i told him not to drive the truck until he can get it seen to i did post on here already but got no reply i think the seal is going bad in his rear differential
p.s. it is a 99 GMC 1500

any info would be helpful