@SvanteE  the WD19TB is already backward compatible with regular USB-C for devices that don't support Thunderbolt.  With those devices, it performs identically to a regular WD19.  If you don't need Thunderbolt at all, then it would have made more sense to just buy the less expensive WD19 in the first place rather than buying the more expensive WD19TB and then spending even more money to buy a module to downgrade it to regular USB-C by swapping the WD19 module in.  But again even if you did that, you'd just get a "permanent" WD19, but the WD19TB can already operate as a WD19 with non-Thunderbolt devices when needed.  So why are you trying to replace the WD19TB module with a WD19 module?

By the way. The WD19TB was cheaper than the WD19. That's why I bought it in the first place.

We use this at home and connect several computers. The dock does not work properly for one of them and I have no possibility to make the required BIOS changes since its managed by an external IT organization.

Now I have ordered a WD19 instead and hope to be able to return the thunderbolt version. I also thought about the possibility to change the module to old fashioned USB-C , since I believe it would be cheaper and I could keep the option to upgrade. 

Modularity is the primary sales argument for this product so it puzzles me that there are no modules for sale.

My question remains, where can I purchase a USB-C module?

@SvanteE  interesting that the TB was cheaper; maybe there was a sale on it or something. Normally it's appreciably more expensive since it is after all a more capable dock.  I'm not sure why it wouldn't work with a particular system, although if it doesn't then I wouldn't be especially confident that the WD19 would behave any differently.  Even if the problematic system has Thunderbolt but has it locked down in the BIOS, the WD19TB should still fall back to regular USB-C operation.

In terms of modularity being a sales point, I'm not 100% sure about this, but I believe that was aimed more at IT departments who stocked dozens or hundreds of these and wanted a quick way to replace the faulty component or upgrade a regular WD19 to WD19TB or WD19DC spec without having to muck around with all of the other cables. In that case, you might have to contact Dell Spare Parts to order that unit rather than expecting to find it in the normal sales channels.  But that's purely a guess on my part.

@jphughan actually I want to do same thing. Looking for replacment from my TB interface to USB-C (DP), why? I have USB device freezes when Im using TB interface. Check this topic for more details: https://www.dell.com/community/Precision-Mobile-Workstations/USB-mouse-freezes-when-Dell-G5-is-connected-to-Dell-WD19TB/td-p/7543027

I have a USB-C module and I'll trade for a Thunderbolt 3 module if anyone is interested.

Please message me.

Yes , i got a wd19 and like to upgrade wd19tb for my Precision 7740.

I tried to buy a thunderbolt cable (Part number 02HV8N) but it can't be found in DELL website ,ebay

The reason i like to upgrade to WD19TB is beacuat it can drive two 27" screen without any issue,

which WD19 can't do it.

 anyone could help me figure it out?

Why is there a permanent USB-C cable on the Thunderbolt Cable Module and also a USB-C Thunderbolt female connector?

Are they both the cable and connector Thunderbolt enabled?

Can they  both be used at the same time?

Thanks in advance