I purchased a 3.4 pulley for my 98 SSEI and I ordered ZZP'* oversized idler tensioner pulley so I did not need a smaller belt. This is for series 2 cars. I work at a auto parts store so I matched everything exactly, so I could find the application he was using to save us some $$

Here'* the info:
Application: 1993 Chevy Suburban 7.4L

Part #'*:
Dayco-89018
Gates or Napa-38007
Goodyear-49007
Murray-209753
4 Seasons-45973

This is a 90mm flat idler pulley, without a flange.

Out of all of these I like the Dayco the best, it is made of a good composite material and has a premium bearing. Walk in price should be around $12.00

You can use the stock belt with a 3.4 pulley on a Series 2 L67. The ZZP idler pulley will help, but it'* not necesary until you hit 3.25", either.

what is that factory size pully??

3.8 for you. Next steps down are 3.6, 3.4, 3.25, and 3.00.

The 3.4" pulley works great

I have also ordered the oversize pulley.
When it arrives and after I install it, I'll let you know how it works out.

The stock belt works fine with the 3.4" pulley but the tensioner is right near the end of its allowable movement.

Will, Have you installed yours yet :?:

In all my years over at club gp I have never heard of anyone using a stock belt after changing the pulley to a 3.4, the tensioner extends almost all the way and especially if there is some miles on the tensioner assembly the supercharger will slip when you get on it.

Hmmm
Maybe because it does have very low mileage :?:

I've been running with it since the spring and the belt is not showing any signs of slippage.....and she goes like a bat out of hell.

Well.. if we're worried about belt condition and slippage.. why not purchase a Gatorback belt ?? They not only last longer then original and give you the piece of mind, but as far as I know they also make shorter ones that will work with 3.4" pulleys and under.. just a thought... things that make you go hummm...

Anyone know if you can run a 94/95 with a 2.5" pulley and keep the stock belt? I'm betting yes. Also need to know if you can run a 92/93 with a 2" pulley and stock belt.

BTW, that belt length and pulley diameter info I quoted above is straight from Pulley Boys. Personally.

I have the ZZP oversize tensioner pulley, but haven't installed it yet. This will be the series 1 test fit for that part. It was originally designed for the Series 2. When my pulley arrives, I'll put both on.