Brendan, if its a striaght replacement, than its just a case of filing in a form at the pits and submitting it (think it needs to be the welshpool pits as they are the technical centre, might also be one technical centre up north too cant remember which) but fortunatley you dont have to show them any other mods you have. if its a bigger motor than what ever it is registered for, than its an issue (not always a huge issue depending on what your doing but may involve emissions testing which is rooted). you will need an engineer eventually (once they catch me lol 7.7L in place of a 5.0 haha) I`ve got a list somewhere in my office I`ll have a dig round for. Also,if this is the case and your going bigger motor into something than I`d say post it up on Antilag, peeps there are alot more in key with motor swaps than I imagine this joint would be. I`ll update once I find this list. regards Ross