I may need a new driveshaft made up. This company http://shaftmasters.com/ from MI
makes 3.5" x .125 walled aluminum shafts for ~$280 shipped.

Does anyone have experience with them?

Hello Dean,
This is David from Shaftmasters Inc. I'm sure the shaft you saw on our website is our "Custom Aluminum Shaft" as an alternative we would like to offer you and any other forum members a complete Aluminum Driveshaft for Camaro applications. Complete shafts come with transmission yoke attached and are high speed balanced with the trans yoke on. These shafts would be available in 3" or 3.5" diameter and sell for $300. This price includes free UPS Ground shipping to anywhere in the continental US. We manufacture 100's of aluminum shafts each year. You can call us at 1-866-912-2004 to order or if you have any questions. This product is not featured anywhere on our online store.
Thanks, David

I got mine from a company in michigan who was recommended by another member, 2 seasons ago. Pretty sure it was shaftmasters.

I got a 3" alluminum shaft with joints but no yoke. Excellent product and service, and my exhaust pipes fit next to it in the tunnel of my vert!