4x4 Differential Problems with Front Wheels

[Levi Luxi]

Hi, 

I have a 99 hilux 4x4 which has a 4" lift in it, the front passengers wheel grabs when 4WD is engaged and causes the car to pull and vibrate, the lift had been completed by the previous owner, this has only recently revealed itself and I have used it in 4WD with no problems before though only in sand. Couple of questions, are both the front and rear diffs meant to be the same? Front end isn't a solid axle. How can I tell what the diff ratios are and what was the factory issued diff ratios for the front and back. Any ideas on the cause of this??