Thanks for the pictures. I pulled the back off this G4242 and it looks like I've only got about 7 1/2" at the most before it hits the high voltage cage. I saw this on E-bay, and while it looks like it might just work, (other than being chrome) it might be about an 1" too long judging by the middle picture (with the ruler). I didn't want to buy it and then be just a tad too long. (looks like about 8 1/2") The basic area where it swivels and collapses looks like the original.
Some of the prices for the "antique" zenith chromatennas are huge.
https://www.ebay.com/itm/New-Old-Sto...19.m1438.l2649
Tony