Read all fourteen pages - and learned a couple of things.
First I did the AD244 to my 97 S10 4.3l - works just like it should!
This is all for a 1997 S10 - others may/will vary.
Got mine from a salvage yard and it is a genuine Delphi 145A has the engraved ID. Took it to Autozone and had them check it, it passed. That way I could take it back and replace it if needed. No need to try it on my truck and find out it's condition.
The belt issue - I had in the past few months replaced mine so it was a good belt, the AD244 fit, though the tensioner was tighter than I liked.
So I got a smaller diameter idler pulley from Autozone a 231098 for $11.99 (Dayco #89098). It worked and the tensioner is right in the middle of it's travel. Told the guy I needed that part number, he asked what it was for, told him riding lawn mower deck, they can't look that up!
The standard pulley is 90mm (3.54in) in diameter. The 231098 is 76mm (2.99in) in diameter.
Want one even smaller try the Zones 231052 (Dayco #89052) $14.99, it is 70mm (2.75in) in diameter. Can not say this will fit as I have not tried it.
Note that the tensioner pulley is 70mm in diameter if your thoughts are that a 70mm will be too small.
Changing the idler pulley was cheaper than replacing the belt.
Then I thought about the belt issues that some folks are having and I wonder if the idler pulley on their trucks is the correct size or not?
This is another way to fine tune the belt tension if you feel the need.
Just my three cents.