Don H, thanks, but I looked there already, and Agena, too. Didn't find a thing at either place, thus this post.
KerryR, I understand about the possibility of field illumination drop off, but I'm not too worried about that, exactly. First, I have other needs for having a 2" sized drawtube option, besides going from a maximum true field of view from 2.38° to 3.35°, I own two accessories that require a 2" focuser-sized slot to function. One is an AstroTech (aka GSO) 2" coma corrector, which will reduce my field of view somewhat with its 1.15x magnification, but would produce a flat field across the near 3° true field of stellar real estate. In addition to that, I also have a 2"-to-1.25" helical focus adapter, for fine-focusing I picked up off Alibaba.com. Since replacing the standard focuser is a little difficult right now (people don't seem to make adapter plates for 130mm tubes), this should take care of fine-focus issues, but again, I need this 57mm-to-50.8mm Synta focuser adapter. But thanks for the tip about contacting Celestron directly. Think I'll do that.
Edited by CollinofAlabama, 04 December 2020 - 10:01 PM.