Diff drop for 3.5 inch lift?

Check out
https://www.headstrongoffroad.com. OME makes lift coils.
I would suggest a 2" lift because our truck already come 1" higher than the previous Gen.

Many thing/issue can come into play when going to a 3" lift on this gen Tacoma. (Because it would be like a 4" lift on a 2nd gen Tacoma.)
Binding of the CV axles at full droop, CV Boot wear, Needle bearings, etc....
I'm running a 2" lift on mine. (Bilsteins with 2887 OME coils) Fits 285's without any issues. I wheel my truck sort of hard. (I've actually needed to replace my front cab mounts already with less than 5k miles on my truck)
For looks? Yes a 3" lift would look much better than my 2" lift. But performance is better with less lift due to better range of articulation of the stock components.
Think of a 3" lift as hiking wearing high heels. Your range of articulation is hindered. (Prone to wheel lift off)

But again you need to figure out what your end goal is, and go from there.
If what you want will require cutting and welding? And possible reduction in component life span. Plan accordingly from the beginning and you'll end up spending less money in the long run.

 

If it comes with a 1 inch lift do you know where the lift is? If I took off the the factory struts and put in a 3 inch strut wouldn’t it be lifted just 3 inches instead of 4?

 

That's a question that doesn't come with a simple answer.

Our 3rd gen coil springs are taller then the 2nd gen by about .5".
So by using the factory coils on a Bilstein you will get 2" lift over stock, but be 3" taller than the 2nd Gen.
If you install the 3rd gen strut on a 2nd gen Tacoma it will lift the truck 1".

So basically our 1" higher stance is due to the longer coils from the factory.