This was posted on a SRT-8 forum where they have a similar group buy.

Les

3/18/11: I am Dana from AUTOTECH Driveline, the manufacturer of Wavetrac Differentials. Autotech has been in business since 1983, specializing in high performance driveline parts since 1986. I am posting here to help Eddie at Southern Hot Rod get information about our new Cherokee SRT8 rear diff to everyone, as we are experiencing delays due to extremely heavy workloads in the plant.
First, we had longer than expected material supply delays to start the job. Thankfully, for this job, we finally got the required material and put that headache behind us.
We are fortunate that Wavetrac sales are growing at a tremendous pace – we think it’s in no small part because we make a well-designed product that is very high quality, right here in the USA. The downside of becoming so popular so quickly is that demand for Wavetrac has outpaced our current capacity to make them. We will not sacrifice quality to close the gap, so we are doing our best to add capacity however we can.
We appreciate your business and thank you for your patience on this project. Please understand that we will do our best to get the Wavetrac diffs to our customers as quickly as possible without losing sight of why they have become so popular – a great diff that you can count on.
Here is the most current information on the Wavetrac differential project for WK SRT8:
There are two main components that are the issues here: housings and side gears.
The housings are made in two pieces. One half has returned from black oxide finishing and will be hard turning on the next available machine. The other half has been heat treated and will join the first half on the hard turning queue late next week.
We have two dedicated hard turning work cells (4 machines total) and there are currently about 4-5 jobs ahead of the WK diffs. This means that the housings for the new diff should be ready sometime in the week of April 11th .
The side gears are the next topic. Side gears are currently being made and are expected to be completed during the week of April 18th. We are working on getting that improved.
Once the side gears and housings are completed and are in hand at our assembly area, the diffs will be built up and packaged for shipment to Southern Hotrod.
We will do our best to improve this schedule. I will post an update here next Friday March 25th.
Thank you for taking the time to read this.
Dana