Regardless of the marking on the chip, the FIRMWARE IS DIFFERENT ON A HTX-10. It does NOT include the firmware required for anything except 28.000 to 29.699.Color me skeptical. Is the firmware inside it the same? That's what really counts. If the chips each have identical markings, that would be a good sign.
Anyone who tells you otherwise has no idea what they are talking about and does not understand how these radios work, OR the significant differences between all of these rigs that "look" the same on the outside.
Unless the PLL chip is changed for one with a different and complete firmware (from a Dragon, Magnum, Titan, Albrecht, etc), or a crystal is swapped out to move the master reference, then the HTX-10 is not able to be modified. And even then, it's literally not worth the trouble. It's not a small job, for a less than perfect result.
It amazes me how long this silly rumor has been in circulation. Decades now, and not one single HTX-10 has appeared outside of the 10m band in all that time (with some simple "resistor mod", or similar). And that is for good reason.