The most current version of the 767 Master MEL (MMEL) can be found at:
The specific item will be in Chapter 28..
Changes to the MMEL drive changes to an individual airline's internal MEL. Some MMEL changes can apply (in philosophy, as well as a technical basis) to other aircraft, and those aircraft MMELs also get changed.
As far as I'm aware, there were no significant changes made after Gimli in the ability to defer a fuel quantity indicator, as long as certain conditions or "privisos" are met.
For example, if a WING tang fuel quantity indicator is inop, a common stipulation is that the airline assure the actual quantity of fuel in the tank by either "dripsticking" the tank, -or- emptying the tank, and then refilling it with a known quantity (as per the truck's meter). Irrective of which ever method chosen, the MEL probably requires that the CENTER tank quantity indicator be operative, and likewise for the engine fuel flow indicators.
The key factor in the Gimli incident, if memory serves, was that while dripsticking, there was a human error made in converting dripstick measurements into pounds and kilograms of fuel. The MEL deferral process itself was (and continues to be) quite sound and rational, if properly complied with...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.