Additional note...

I called out a single 12" tube for your clone, whereas the original model used two tubes with a coupler to make up the 12" length. Personally, I'd go with the 12" tube and a TB-7 thrust ring internally, with a 24" length of SEMROC's Kevlar thread tied around it for the shock chord mount. I'd dare to say none of us on this forum use the old Estes method for attaching mounts anymore, unless we're in some kind of competition for classic designs where "modern" construction methods are frowned on. We're a very progressive bunch of coconuts on this forum...

If you absolutely insist on staying with the old method, then you want to use another 3" length of tube for the motor mount, and a 9" length forward of that. The SEMROC part number for that tube is ST-790. The internal coupler is the HTC-7.

Go with the 12" tube. It will make the finishing stage much simpler. One less butt joint to sand and fill...

Besides, no one has to know it's not an original kit...

Craig...