How long of a truss rod do I need?

[Hollowway]

I've got a bass that I bought that has a busted truss rod nut (don't ask) so I want to build a new neck. But I want to do a longer scale. Anyone know what the truss rod length on a Dingwall is? I want to do 37", so I'd like to know what length to get. And if it seems like this is a stupid question that would only be asked by someone who has never built a neck before, then you would be 100% correct, lol. But I can't find a definitive answer online. Some people say have a custom one made, and others say a regular 24" would be fine.

 

[PatF]

For a 37" you would probably have to build a body too. Throw a Warmoth on there or pull the fretboard.

 

[Hollowway]

For a 37" you would probably have to build a body too. Throw a Warmoth on there or pull the fretboard.

I can't, because it's a 37" headless. I planned to just extend it at the nut end, so the intonation stays correct. And, if I can find someone else to build a neck, I'm still way more wanting to do that, than hack away at it myself.