My 2001 Jeep Cherokee Laredo says next to the shifter SELECTRAC.
When I look up fluids in the Amsoil website they (mainly for the differentials) list Quadra Drive and Vari Lok and W/O Quadra Drive. Do I assume I am the W/O Quadra Drive?

They list several fluid choices for each differential. I live in NY, and was going to just get the 80W-90 for front and back diff.

Also for the rear diff. they list a 194, 198, 216 and 226 with different capacities. How do I know which I have?

Is it a 4.0 or 4.7? If you have a 4.0 your transmission is a 42RE and if you have the 4.7 you have you have the 545RFE. Both take ATF4. With the Selec-Trac you have the NV242 transfer case. Also takes ATF and since you don't have Quadra Drive or Trak Lok diffs 80w90 would be fine for the diffs.

Wait, It matters if it is a Cherokee or Grand Cherokee. The Cherokee is an Asin Aw4 transmission and comes with either a 242 or 241 transfer case, both of which all use Merc/Dex fluid. Grand Cherokees had the other options for t-cases

Woops!! I see it's a Cherokee not a Grand! My bad.

Sorry not be concise. Its a 2001 Grand Cherokee Laredo with a 4.0 6 cyl.

So how do I figure out the capacity of the rear diff. It can vary by several pints depending upon the Rxxx number.

My rear diff took just over 1 quart. If I were you I would buy 2 quarts of 80w90. No need for 75w140 unless you tow.