[cleszkie]

From the sounds of it, swapping in an overdrive manual tranny will not completely fix your drivability problem. You have some pretty low gears in the axles (high ratio). An overdrive tranny might get you near a 1:1 drive ratio when it is in its overdrive gear. I recommend not spending the time, effort, and money on a T5 swap. Rather spend some money and get your axles re-geared to something like what came in these Blazers originally when equipped with a manual (3.37:1 - I could be off on this number), or if you just want to fly down the highway, go for a set of gears that these Blazers came with when equipped with an auto tranny (3.08:1).