I'm noticing a difference in gear ratio variations from Dana diffs and Ford diffs. My concern is if I have 3.73s in my front dana 30 and 3.70s in my rear Ford 9 inch, will I blow something up? How much variation can I have between the two diffs? I know it's best to have them match, but there's no matching gears between a Dana 30 and a Ford 9 inch.

 

I would say your fine unless you try a 4 wheel burnout on pavement.

 

something that small is okay, and wont hurt anything imo

 

you will be fine off-road. just be gentle when on pavement. but low tire pressure would probably make a bigger deal then ".03" in ration difference. if you cant get closer of a match run it.