Originally Posted by Heavy_Metal_Thunder_81
GM NV4500 would work.
x2 on the GM NV4500 ideally. feasibly an AX-15 & NV3550 5 spds or NSG370 (6 spd) found in later model XJ/TJ jeeps could be adapted. Novak and Advance adapters cite they can hold up to V8 power but these are not heavy duty trans like the NV4500. FWIW i have an SM465 4spd behind a 5.3L LM7 in an offroad rig and while it handles the load no problem it shifts like an old dump truck.
A quick search of 'max input torque ratings' for some of these offers the following informal list for comparison:
- NV4500, 460 ftlbs
- AX15, sources suggest similar to NV3550
- NV3550, 300 ftlbs
- NSG370, 272 ftlbs
- SM465, 465 ftlbs (non synchro 4spd)
Other 4spd options NP435, SM420, T18, ...
Not sure what LS you're planning on, but a search for a run of the mill LM7 suggested they can output around 325 ftlbs peak torque stock.