I have been using the stock belt with a 3.4 pulley and larger tensioner for sometime now but I think its begining to slip. What is the next smallest size belt I can run on a 2003 ssei? I have seen the posts before but have been searching not finding size/ model numbers.

thanks

I'm running a 4060715 belt with the stock tensioner pulley. If you want to go back to the stock tensioner pulley, you can use that belt.

correct Dick....

the stock belt on a SSEi is a 725 belt. When you go to a smaller pulley you have 2 options.

install a oversized Tensioner
or
changer the belt to a 715

can I use a 715 size belt with the oversized tensioner? I have this enoying squeek and when I apply force on the belt it goes way

No. One or the other. 715 belt preferred with the stock idler over stock belt with the oversized idler.

Oversized idlers work better for the S1. Shorter belts for the S2.

Sorry I dont know what a S1 or S2 is? Please explain

Series 1 L67 from 1991-1995.
Series 2 L67 from 1996-2003.

You have the latter. Shorter belt, stock idler for you.

I am runnin 715 with my 3.5 pulley stock idler and its pretty tight. I think it would be same for 3.4

The 715 is plenty tight for my 3.4 also. If you still have problems after returning to the standard pulley size, and going to a smaller belt, you may need to replace the tensioner.