I was thinking of swapping from Automatic transmission on 86 4Runner to manual. I have parts vehicle with all of the necessary parts and even computer. What I am curious about is can I swap 3rd members in rear and front axle so the gears are correct for 5 speed or do I need to change entire axle?

 

You do not have to swap the entire rear axle just the "third" member. the front if it is still ifs will come out a a whole axle section minus the cv axles. I would recommend doing the five speed swap first and drive it before you change axle ratios.

 

likely than not they both have the same gears. most have 4.10s, the auto could be 4.30s, I cant remember exactly what year those came in but I had an 88 with the auto and it had 4.30s. the front clamshell is removable but its easier just to pull the whole thing in my opinion. the rear third is straight forward, slide the axles out a few inches, pull the third.