The V8 Owners Forum -

Blown 3.5v8 street use only car, would LT77 be strong enough?

Depends.

How much power, torque, traction, vehicle weight, and definitely which LT77.

Before I have up with them on my 3.9 TT many many years ago, they'd last a short while. I bought a few cheap from a 2.0 assuming the gears were the same. I broke both of them within 20 minutes of fitting lol
The V8 versions did last a bit longer.

So they're not strong by any means. But when the car was n/a and even when turbo'd with not a lot of boost, the V8 LT77's would last a while.

I eventually moved to the R-154 which lasted very well, this was all back in the 90's though

There will undoubtedly be stronger options around now and perhaps more readily available if someone makes adapters for them

From a cost perspective, just run it and wait til it breaks. Then you'll know if you need to change it or not

I would go R380. This is what I have in my Landie, which is a 4.6, fast road cam, ported heads, large bore manifolds and high compression pistons.

I got it 'new' from Ashcroft Transmissions with all of the strengthening mods they offer.

Chris.

LT77 was fine (didn't break) in my 3.5 supercharged kit car (something like 600kg - probably around 250bhp but never dynoed) Did a couple of drag races but mainly road use, but obviously that super light weight means it's quite an easy time for the box!
When I switched to my 4.6 supercharged I also fitted a T5 from a TVR which is stronger and lighter.
shock loads are what can kill gearboxes - so road use is much kinder than drag use and launching them.