If you could find a front axle with the same ratios as either your rear hi or lo you could potentially run in that ratio w/all 6 axles. You would have to have a fail-safe method of ensuring that your rear cannot be in the wrong ratio with the front axle engaged. A mechanical linkage would be the only feasible method. Electric or vacuum shift would have a chance for the rear to not shift and screw things up.
You keep referring to rear axle, in the singular. Do you have a tandem rear now? If now you would need to find a tandem rear anyway to be a 6x6.
Tad
1946 Chevy OS 1.5ton, 1955 GMC 3100, along with other various IH,Ford,Nash,MGB,.....
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