Anyone know if I can switch my 5 year old Adsense accout to a gmail user from yahoo user?

you should contact with google support and hope that this matter will resolve ask them to change the username and then shift on gmail.

If i were you i would rather contact Google. I think they are in better position to tell how to go about this if it's possible.

Good luck

I had found this information on Google's site, but not sure if it applies to me:

Change of email or payment address

To update your email address, please follow these steps:

There are two ways you can do this:

Edit your Google Account

You can change your email address/login by editing the Google Account you use to access AdSense. This is only available for non-Gmail addresses and affects all of the products that are linked to your Google Account.

Associate a different Google Account as your login

If you have Administrator access, you can invite a new Administrator, log in as the new Administrator and then remove your original Google Account login.
As an Administrator on an AdSense account you can also add and remove Google Account logins for an AdSense account. Learn more about managing access to an account.
download To update your payment address, please follow these steps:

Sign in to your AdSense account.
Click the gear icon and select Settings from the drop-down list.
In the "Account information" section, click edit address, then make any desired changes

Anyone know if it would work to just signup a new analytics account with that same yahoo address that's associated to my Adsense account, and then just add my website to that new analytics account?

I saw an option to link my adsense account to analytics, and when I clicked that link it just too me to the signup page to analytics, but still showed my yahoo account at the top of the page.

S.