Paladin mount size increase

[Yomega]

Hello everyone I posted this in the Q&A but it apears its not as simple as I thought and my situation also requires some thought.

The character Im building is Ranger1/Paladin6/Griffon Rider2
Griffon rider is from unaprochable east it gets a speacial griffon mount that stacks with the paladin speacial mount.

To the best of my understanding it starts with 7hd and you gain 4 more from efective paladin level 8 bringing it to a total of 11 hit dice and the monster manual sais at 10 hit dice it increases to huge size.

So I want to know if I understand that correctly and on a side note if it gwts d8 or d10 hit points for the 4 new hit dice thanks.

[docnessuno]

Oddly, both HDs gained from Paladin and Griffonrider features have a specified size (d8 and d10) but not a specified type. The fact that the PRC is 3.0 and both special mount and creature types were altered in 3.5 doesn't help.
RAI it's clear the the paladin is designed to add Animal HDs (even if the mount is a magical beast) and the Griffonrider is meant to add magical beast HDs, but RAW it's unclear.

If i had to make a pure RAW judgment call i would say you add HDs depending on the base creature type, altering their size depending on the table used (d8 if using the palading table, d10 if not), so a Griffonrider would use d8 only if he decides to designate his griffon as his special mount.

Edit: Note that, due to the paladin's mount rules, if a Griffonrider designates his griffon as his special mount, the mount would have medium BAB and good Fortitude and Reflex saves, regardless of its type.