My notes on LA alternatives contributed by posters over the years:
1985 Corolla GTS "AE86"(4.25)
Rear Wheel Drive Corolla GTI, which is known as the "AE86" by all of the Toyota buffs.
RX-7 GSL (4.25)
If you looking to keep originality I understand, but if you want a good light strong axle look to the early RX-7. If you get the GSL-SE model they come with disk brakes and a LSD.
* a caution on LSD, just because there is a plate LSD is not a reason to pursue it. The ramp angles are tuned for the original application which is a much heavier car. I was advised by Arnie Webb that 7s like 0° exit ramp because we come off the the throttle si quickly. In most cases, an open diff is adequate. I could be wrong.
MV8:
You might consider an axle conversion to an equivalent that came with a 4.30 ratio (maximium), like the Toyota 10 bolt 6.7" ring gear axle used in dwarf cars, just not severely shortened on the right side. For a used axle, look at 82 and older corona, 84-87 corolla GTS, 74-79 SR5, 71-85 celica ST and GT. I expect there are parts available for these for racing. They came with either two or four spider gears and an open or limited slip.
A Ford 8 inch is a common axle here that is built like the famous ford 9 inch only smaller and lighter. I think it was used in the H&S Seven.
Birkin factory in South Africa that the rear axle was a newly manufactured unit as used in a Toyota Hilux minivan manufactured and sold in South Africa. The only ratios I have ever known of for those rear ends were the two that came in solid axle Birkins. 4.11:1 until early/mid 2000, then 3.89:1. My kit landed in the US in September of 2000, and it has a 3.89
I have heard some mentions of Datsun B series axles, but good luck finding those.
I may update this post later wirh more info.