Do you want to get an idea on how your 4x4 would perform if you:
- used a different tyre size?
- replaced diffs to one with different ratios
- got that 5 speed gear box that you have be itching to get
I hear a round of NOs, but here is the gear ratio calculator that gets you the RPMs at various speeds and final drive ratios. You need to have your transmission, transfer case and diff ratios at hand for the full results.