Yes it is
I use Mercon. My 98 S10 5 speed now has 178K with no problems.
I have a 98 S10, 5 speed standard with 185K miles on it and I use Mercon in the transmission.
Yes, both transmissions are the same.
I get 12 to 18 mpg with my 91 s10 4.3 4x4 5speed
18 gallons
If the engine size is the same, probably
If you have the 4.3 L engine, no.
No they are not the with of the stud holes are different.
yes, most of the parts are interchangeable from the blazer to the pick up.
Yes
Yes
Yes