70hd locker for towing?

[80' 427]

I have a 82 6.2 diesel dually that I am working toward making into my farm truck. The plan is build a solid diesel add a nv4500 or ranger 465 ( both in the shed). What is everyone's thought on a locker for a dually that may tow up to 18000lb fifth wheel. I have 2 detroits in other trucks but I don't tow with them. Will it break or break axles?

 

[Stomis]

Get a trutrac. Its somewhere in the middle of the road between a full locker and a posi. It works when one wheel is in full slip like a locker but it differentiates between wheels via a gear system unlike a clutch posi. I had one in my 8.5 behind a 400hp small block with a 5 speed for a few thousand miles so far and it is awesome.