I posted a couple of days ago about my 3520B tailstock sticking. I determined that I needed to replace the Quill and Lead Screw, but found that Powermatic has the quill for the 3520B on backorder until atleast August. Not satisfactory!! I went to work calling all distributors and found there were none in stock. Then I contacted Craft Supplies and talked to one of their techs who told me that they had found that the 3520C Quill and Lead Screw fit the 3520B. That's great news!!! The 3520C screw set up is a acme thread as opposed to standard threads, and the advance rate is almost 3 times faster (6tpi compared to 16tpi). This would be a huge improvement to the 3520B tailstock operation, plus the acme set up is much more durable. Just thot you'd like to know!!!