Mesl Me 70-24
 

Does anyone have any information on this.
ME 70-24

I guess it has to do with a fuel quantity indicator?
It’s not an AD or SB but similar.

Is someone asking you to comply? I don't know if that specific item is for USA, I think it's New Zealand. Do you have more details?

The fuel indicators issue was an AD back in 1970 that required a scat vent to blow air on the quantity indicators. Can't imagine there would be a 337 out there that does have it complied with already. Not sure if it affected all models but the pre 1970 models had to comply

yes to blowing on fuel gauges
 

Yup. I discovered that one years ago after buying my 337 and having a fuel gauge smoke on me. They run hot. Amazing. Mine is a 1969, same tech that went to the moon. Scary.

After an annual a few years ago an A&P forgot to reconnect the little air hose. Sure enough, over GA, smelled like we were flying over a forest fire. Another used gauge from Texas air salvage.

The weird thing is the gauges have four connection points. Seems like current runs through a coil plus current through another winding. Every other gauge in the known universe has two pins, these have four each. Won't work if you just apply current across two.

The wires get warm, the insulation breaks down, then they short and toast

So yes, it is needed, and does make sense, in a 1969 sort of way.