If you aren't aware, Tremec just released it's TKX transmission, which is the evolution of the T-5/TKO500/TKO600 line. It now has triple cone synchros and a stiffer case, extending the usable shift RPM to 8000. This seems very promising as a no-compromise strong 5-speed box.
https://www.tremec.com/menu.php?m=183
Let's list some advantages here:
1. Lighter than a Z33/T56 box by 30lbs
2. Rated for 600lb-ft of torque
3. Massive aftermarket support
4. Available basically everywhere
5. Will be in production/service for years
6. Removable bellhousing
7. Mechanical or electronic speedometer drive
8. Compact
9. Shares bellhousing pattern with G-force dogboxes/others
10. Close ratio gearset
Adapting these should be relatively easy, with an adapter plate and a bellhousing from your preferred engine (auto SR/KA/RB, R154 JZ), a custom pilot bushing and a 26-spline clutch disk in your required diameter.
Here is a example of a G-force GSR to SR20 adapter:
I do believe they would need an extended shifter based on how the TKO fits in an S13:
Retail is $2,795 for the gearbox.
Anyone else think this sounds pretty good? I think it's something to talk about at least.