When looking in a salvage yard
what vehicle and year
would have the Dana 61 with 3.07 ?

I would like to get one to replace a Chrysler 9.25 with 3.21, or I would like to find a QuikChange diff.

Back in the 1980s
there was a guy near Mt Vernon KY
who just personally liked cutting gears
and had an extensive shop with much older gear cutting machinery.
He could make nearly any gear style including hypoid and did one-off jobs for the mining and trucking industry.

I am not sure if he is still alive or still working.