Which Dinitrol for external parts of my chassis?

I will be applying Dinitrol ML 3125 to the internal parts of my 1998 Defender chassis and bulkhead to protect it. However, I'd like some guidance on which product to use on the exterior of the chassis. I had assumed it would be Dinitrol 4941, but the guidance on the Rejel website (Dinitrol supplier) says I should actually use Dinitrol 445M black stone chip (when you buy their kit). A quick search of commercial applicators of Dinitrol suggests that Dinitrol 4941 is used on the exterior of LR chassis, but I want to make sure I am applying the absolute right product for the job.

So in summary, should I be using Dinitrol 4941 or Dinitrol 445M on the external parts of my Defender's chassis? Also, are there any pros and cons of each product e.g their application. Thanks.

I used 4941, def recommend it, gave a really nice finish

+1

This is an email I got from Dinitrol.

Hi
Internal, you can use DINRC800,this will convert the rust to a hard, stable organic compound.
External I would apply a very thin coat of ML3125 cavity wax to the chassis as it contains rust inhibitors and will act as undercoat for the underbody wax 4941(black) or 4942(brown)
For wheel arches and high abrasion areas then use 447 in place of 4941,4942 but still apply the ML3125 first.

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The only con I have seen on any vehicle with a hard type wax undercoat is rust bubbling up underneath the coating.