I think that if the plastic frames are original to the tank they should be identical in all measurements.
I think what the OP is asking is what is the width of the plastic trim underneath the tank where it contacts the existing stand.
I just measured an older 125G tank I have empty and the top and bottom trim width is approx. 1 inch wide, however don't forget that the glass doesn't fully occupy the plastic trim gap space. The glass is closer to the exterior portions of the plastic trim and will be about the width of the glass panels. So if the tank glass is 1/2" thick, that means you will need support under that 1/2" dimension rather than under the 1 inch width of the plastic trim.
Eheim Pimpette #270
Eheim Pro II 2028; Classics Series -2215, 2217, 2260, 2262; Pro 2229 Wet/Dry
Last edited by deeda; 09-15-2020 at 07:11 PM.
Reason: add info