That is the standard axle for the v6 1st Gen. It's designation is H233B. I has a 233mm ring gear. The closest comparison would be a Ford 9" rear axle. The "49" means you have the preferred 4.90 gears. The rear axle on the 1st Gen is an absolute beast.
The front diff is an R200A. No slouch either. The drivetrain on the 1st Gen is pretty much bulletproof.