Here is my profile for proof:
http://us.battle.net/d3/en/profile/sahkuh-1946/hero/41090951My power leveling method was mainly for my original level 60 characters.
If you have a level 70 friend that can spare about 20 minutes, it speeds up the process a bit.
If you have a high level friend, have your level 60 character make a T6 campaign game. Make the quest "Royal Audience" in Act 2 and continue into the instance. If your friend is geared decently with ilvl70 items, he should stomp all the white snakes. Exit the throne room and rush towards the sewers. I found that killing the extra pulls ("Snake Runs") wasn't very efficient and it was better just to complete the quest for the 10 million+ quest XP.
Continue doing this until your friend gets wiped in the first snake wave. For my friends, it was usually around level 65.
This is where you go solo.
Make T6 games in Adventure Mode. You will be looking for 2 bounty quests and 1 random spawn quest.
Act 1: Cemetery - The Jar of Souls
Act 1: Cemetery - Matriarch's Bones
Act 2: Howling - A Miner's Gold
Act 3: Rakkis Crossing - Crazy Climber (not a bounty)
Check to see if the any of the 3 bounties have spawned. If not, go to Act 3: Rakkis and see if Crazy Climber has spawned. All of these quest don't require you to kill anything. You talk to people and click things. I was getting about 11-14 million depending on your level. Miner's Gold gives you double the XP because of quest and bounty XP.
If the RNG gods are screwing you or you start getting bored. You can also do the Rumford quest.
Make campaign game and choose Rumford's Quest in Act 1. Make it on Normal.
Kill 2/3 Wreaked Mothers and then quit the game.
Change it to T6 and resume the game.
You will be and town and there will be a Wrecked Mother right outside.
Lure her INTO the town. It should instant kill her.
You will get about 10 million+ XP and some gold.
Some tips:
You have to be alive to get the XP, for all the quests except Miner, you will be alive since you talk to someone to it in. Miner will auto complete after a certain amount of time. I found that standing on the bridge below allowed you not to get aggro'd.
http://i.imgur.com/ZDKYM86.jpgCain's gear and other +XP items (Hellfire, Ruby Helm) DO NOT affect quest XP. However, Pools of Reflection and XP shrines DO! Sometimes, if I got a pool, I would do Rumford's quest until the pool was used up. You will die a lot doing this.
Open all chests that you see. At T6, they will drop a lot of legendaries. I found about 10-15 legendaries from chests or quest rewards. Most of them I had to salvage into Forgotten Souls, but hey, more rerolls for ilvl70 gear.