Has anyone had experience in a changeover of the 21axp22 tube
to the all glass tube?. will the tube shield fit over it in order to
easily use the yoke. Is there a parts mod kit out there that is in
someones junk box, The set is a CTC5, Thanks for all info

The shell won't fit, I know that for sure. Used to be a kit, but it's very rare now. Best thing is fab your own support stuff from brass if possible, try not to use anything magnetic.

Here are pix of my home-made adaptation:
http://www.flickr.com/photos/42002845@N02/sets/72157627018247265/with/5913717501/

It didn't seem to make a noticeable difference that I did not do everthing in brass.

Just save the original parts in case you ever do get a good 21AX.

Edit: note that the pieces near the face are the home-made part, the mounting ring and straps are from a later chassis - but you could fabricate something similar, I think. I also recall that the small hairpin magnets were helpful in getting uniform purity.

Pics of mine with adaption kit. Not done by me.

RCA's conversion kit included a standard CTC-7 and up type yoke cover which replaced the CTC 5's original cover and secured the yoke to the CRT neck instead of the plastic cone originally used in conjunction with the 21AXP22..