Id just top that off to start an elimination process, possible trans service? Maybe the trans. filter and trans oil need change? Dont know if checking the diff. will help but might as well check that too.
Well I had a 93 S-10 pickup and an older S-10 Blazer both gave me trans problems but both of them were manual. The noise you described sound as mines did when my throw out bearing needed replacing so I changed the clutch and all. If it sounds as if you have gear drive then it may be worse, sorry to say but in that case your trans will need repair/replacing. My shift stick would pop out of gear then eventually that gear would become unavailable. Again this is with my experience of trans issues with it being a 5 speed manual. Hope this isnt the case, goodluck.