i recently took some heads in to get valves and springs installed and since this is a freshen up of newer heads and the machine shop didnt have my set up he didnt order my rocker arm studs he said he didnt want to order me the wrong ones. so how do i know what one i need? they are dart heads with a solid roller cam i dont know what info will help but i need to get this show ready for the road before snow melts. i do know i need 3/8 studs but what length. i never knew this mattered until the machine guy brought this up