The diff varied by model and year. The non turbos had a 4.30:1 for all years. The non-US market 1JZ equipped vehicles had a 4.10:1 torsion available but it won't hold much past 450RWHP.... depends on the driver... it's not a popular swap as the regular LSD is much more robust and available. The US Turbo models had a 3.93:1 until '89. '89 and newer had a 3.73:1.
The stock LSD is VERY robust and will take a lot more than 400HP at the wheels... especially if rebuilt. The axles are also no problem as long as age hasn't taken it's toll on them.
Some people have swapped in different (domestic) units but under 500-600 RWHP there's not much point (they've been shown to be reliable beyond that level). Some people have had the stock unit crash on them at lower power levels but age is more likely to blame than frailty as a number of people have really put them to the test in high power applications with no problem.
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