My main concern is the o/d. Can someone please help me troubleshoot it.  It does not engage the o/d unit.  It goes into freewheeling but that's all. 

I'm also trying to figure the rpm's at 50 mph running in direct 3rd gear.  I am having trouble with the calculations. I know input to the 3rd member is 1:1, a 3.89:1 final drive, and an 89" circumference tire.  A functioning o/d will reduce this number by 0.7.

TIA