Differential housing. The factory setup for the front differential housing material is cast aluminum. This is light weight but under heavy load can cause deflection of the pinion. Trucks that came stock with a manual transmission also came with a cast iron front differential. This housing is substantially stronger than the aluminum housing and can be swapped in with no modifications (assuming both diffs have 3.73:1 gear ratios).
Axle tube. One of the common complaints from S10 owners is that the four wheel drive stopped working. These vehicles are equipped with a two-stage shifting process. First the transfer case shifts into 4HI (or 4LO). That opperates a vacuum switch that sends vacuum to the front of the truck under the battery tray where a module uses the vacuum to pull on a cable to engage small sliding gears on the right side axle tube. Any one of these things can fail (switch fails, vacuum loss, vacuum diafram fails on the module, cable binds, gears bind or are stripped). There is one S10 based vehicle that omits all of this... the Oldsmobile Bravada. Because it is all wheel drive, there is no reason to have the front axle dis-engaged. This is plug-n-play for the S10s. This also eliminates a weak point in the axle (the sliding gears only engage about 1/8" - 1/4" of spline.