I have not had my suburban for very long, so I really don't know much about them. As such, I was wondering...what type of axles do they have, in particular a 1989 v1500 350 4x4 with 373 gears? And, the previous owner had purchased 31 inch tires for a more "aggressive" look, which I love. However, at highway speeds of 55, I have to shift into overdrive. And if I go below 55 in overdrive, the engine really seems to lag. So, would putting in, say, 342 gears fix that? Thanks for any help.