Where’s the belt tensioner?!

Anyone know where the tensioner is on this double v belt system?

what are you trying to tension?

V belt systems don't usually have a tensioner.  If you look at the first picture you have you can see the belt between the crank and alternator.  The tension on the alternator belt is adjusted by loosening the bolts that hold it slightly and then prying between the alternator and engine block, holding the tension and tightening one of the bolts down to hold it before tightening the rest.  I don't know the specific amount of deflection that is specified, I'm sure someone else can chime in with that.

On the bottom picture it's the same procedure, loosen the bolts a little and then pry,  the bolts follow the slotted holes.

Okay cool. I’m trying to swap out my alt so I guess I’ll just take off the screws on the slider mount and then when I put the new alt on just pull tension and tighten?

yes,

You'll loosen the bolts that hold the alternator, this will release the tension from the belt.  You can then push the alternator towards the engine, it'll swing on the upper bolt(s) and then you can remove the belt.

Then remove the bolts completely and disconnect the connectors.  Obviously have the battery disconnected.

when you're resetting the tension, lightly snug the bolts up so that when you're prying on the alternator to set the tension you only have to tighten a 1/2 turn or so to snug it up.  I usually aim for ~1/2 in deflection, but I don't measure it, it's just an experience thing.  Too loose and the belt slips, to tight and it's added strain on the bearings.

You'll have to retention the belt after a month or so, it'll start slipping as the belt stretches.

I use one like this to tension mine with. I didn't have one for the longest but decided to get one since I have so many with v belts.