I'll jump in here...

There's a tensioner that keeps the chain taut. But, at 80k miles, and you're in there anyway, you should definitely replace the timing chain set! (And inspect the cover.) The steel backed guides cost a little more. I like http://stores.ebay.com/Mizumo-Auto-Parts for parts!

'92 Blue 4WD ExtCab 22RE 5spd A/C
'89 Blue 4Rnr 3VZE 5spd A/C
'89 Black 4WD Std Cab 5spd 22RE A/C
'89 White 2WD Std Cab 4spd 22R A/C
'78 Orange 2WD LB 5spd 20R A/C