Just type in the Truck make and Oil Pan replacement.

no luck

Garage. Or,just plain Engine Oil Pan repair. Sorry,watched a couple of these Tubes a couple years back in order to help my Bro fix his .

will pretty much walk you though the repair.

Oil pan doesn't seem too hard of a job not knowing what the truck is. You probably checked the youtube videos. That's where I've always found decent videos for anything I wanted to do repair wise. Definitely get the book and read through the procedure to see if it's something you want to tackle. Generally speaking a good repair manual will pay for itself with just one job. Haynes is a pretty good brand from my experience.
God Luck

The engine needs to be lifted a bit, I guess. We do have the capability to do that here at home.

for repairs on their vehicles and yes they are helpful. But if you got an estimate for $1200 that sounds like it might be very labor intensive. Is your guy good with repairs?

The post above is good advice, my guys also find repair guidance videos on You Tube.

There's something about the 2003 Tacoma (some sort of a first-generation for how the engine sits in the frame of the truck) that does indeed make it labor intensive.

We didn't find anything on YouTube.

The labor intensive part is the front differential has to come out so the pan can be removed. A friend had a 02 that he went offroad with and cracked the pan. Took an entire day to drop the diff and everything else out of the way to get enough room for the pan to come out.

my neighbor's Volvo actually cost more than that.

My mid '70's Dodge van had a notched pan to fit over the axle a friend of mine figured out that we had to take the engine off the mounts jack it up on a board between two floor jacks and turn the engine about 15degrees, but we got it done.

according to how my guy talks about it.

I think he wants to be sure he's disconnecting what needs to, and leaving what needs to be left alone.

They are a solid source for auto repairs.
Just take your time, read, look and understand each step.

filling the engine bay to the 1/4 inch. Chilton's has online manuals. Might look into that.

Shouldn't be a major issue unless you have to remove supports or parts of the suspension to get to it.

They may not have every procedure - I'm not sure how common an oil pan replacement is. As with most things under an engine bay, getting to the part often involves removing several others for access, which is time consuming, hence the $1200 estimate. Even if this is more than your guy wants to attempt, I'd pick up the manual anyways for do it yourself maintenance and repairs - it's a 16 year old truck. Pretty much the first thing I do when I buy a used vehicle.

It's possible to end up with a giant hole in your hood. Here's an example from the cover on the manual for my Honda:

https://haynes.com/en-us/honda/accord/2013-2017