I´ve been trying to find specs and info about this car, but it seems scarce. What I do have found is that the engine used in 405 T16 GR that won Paris - Dakar in -88, was the same as the 205 T16 rallycar. Other than that the chassis are different from the 205, and pretty much everything on the 405 is different from the 205.
The Pikes Peak version of the 405 I have found just about nothing about, but it seems as it has another engine than the P-D one (not sure though).