Beauty truck!
Figure out the speed range you want for pushing, what diameter tires you will run and gather a bunch of gear ratios from the transmissions you want to run. Then hit one of the speed calculators available on the web. There are many and are easy to use (especially on some of the 4x4 sites). Start plugging in numbers and you will find the ratios you want.
Ref the SM420: I top out at 8-10 mph because I won't run my 60 year old 216 splash oiler over 2800 rpm. At 6000 rpm you would be roaring up to 20 mph! Speed Demon! LOL!
Current fleet (subject to change w/o notice) \'49 GMC 3/4-Ton , 60 Austin Healey Frog-eye Sprite (some assembly required), 2011 Dodge Avenger, 2015 Jeep Cherokee. No, they don't all run. My other ride is a (B737)no, (B767)no, A320.... Update... was Embraer E190, now Boeing B787. Knowledge is a wonderful thing, but ignorance means you don't know you can't do something.
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