So if you assume that fuel can be turned up to get max RPM out of the engine at full load (not likely w/o meltdown!) you can theoretically go 107 mph at 3600RPM!! More reasonable is that it'll pull 3000RPM, which equates to about 90mph. On 31's.
Headwizard, M1009 axle ratio is 3.08. You're thinking M1008, which have 4.56 gears.
3000 RPM in my M1008 only gets me a little over 60mph.
Hopefully a 700R4 and some 33's will get me a little better cruising RPM... About 2100RPM at 65mph, which isn't too bad.
And I believe that most highways have "safe" speed limits posted, usually between 55 and 70mph.
(A 1009 is just a chevy blazer, and there shouldn't be an issue with a blazer doing the speed limit.)
Chris