I inquired about purchasing a 8 3/4 center section from Dr Diff last summer and he said he was not currently assembling any more due to being too busy and not having enough help. I ended up purchasing the parts from him as a complete kit just needing assembly and took them to a local driveline shop who charged me $225.00 to set it up. I thought that was pretty reasonable as I do not have the knowledge to do it myself. There is also an ebay seller 68lo23 out of AZ that sells a lot of these units already assembled and seems to be pretty reputable although I have not dealt with them personally. There is another seller drivelineworks out of FL that sells them as well. I have done business with them a couple of times and they were great.