93 3.9L. W/ac. W/ps. New topic about an old thread. Turns out my coolant is leaking from timing cover. Took it to the shop. After I got home I did some searching on cost estimators. They came in much lower with labor hours being less. Then, I signed up for free trial of the auto labor guide used by mechanics shops. That calculation was right at what I was quoted. So, that's cool. They said as long they're there it makes no sense to not replace the chain. On the calculator replacing the chain was over an hour more labor then just replacing cover. That long once the cover is off?
Curious.

FYI. Timing Chain and tensioner, parts and labor $450ish

 

No idea which online calculator you were using.
But I can tell you that the ones the shops use, like Mitchell are accurate.

They usually list a base time for a given task, then additional time for extra tasks or also things that complicate the job (like your truck having AC)
Something like this...
timing chain = ## (includes R&R timing cover, timing gasket, pulleys, belts etc)
Crank gear = add #
Cam Gear = add #
AC interferes = add #
Air pump interferes = add #

So they are detailed and accurate, for a job on a new vehicle. (or one in great shape)

In fact it usually works to the customer's advantage, because an old vehicle takes more time due to rust and other hassles.
The estimator lookups don't account for that.

Shops that charge book time and stick to their quotes (due to law or just honesty), many times end up spending more time on the job than they actually charge for.
Unfortunately for shops, there is no "add ## for old vehicle with rusted parts and covered with grime."

 

This is the one that reflected the cost I was quoted. It had high, low and average. My quote was about in the middle.

https://www.autolaborexpert.com/

Other online were different.