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I'm sending an AC dual stage fuel pump to Then and Now
for rebuild. TM9-8012 pg 162 par 131-B fig 48 describes
pump body modification for a 1/8" oil return hole drilled
in the pump body to minimize premature pump failures.
I'll request that they perform this task during rebuild.
Do you guys rccommend it, what about your experiences??

It's one of several standard upgrades that later pumps came with already. Reputable rebuilders have all the update service bulletins and usually make the changes automatically.