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Ok, so I read the gear ratio info on the "CRUZIN" post. This got me wondering. I always asumed I had the factory military gears. As I never left 3rd gear driving in the backyard before I parked her and began teardown, I never got near 45 let alone 55. Now I did find it odd that when I disassembled my axles the carriers had only nylon locknuts and no lockwashers? I thought nothing of it and figured somebody had been in them before. I did not bother to count the teeth or measure the ring gears.
Today I got to thinking and realized my truck had originally come from Memphis Equipment before its life as a crash/fire rig at Cape May county airport in NJ. I had gotten the original parts manual with the truck. So into the den I went to dig for that book. On the cover it says "highway speed 55MPH". Did all the Memphis reworks have 4:89's I wonder?So now that the axles are together, how do I tell which gear set I have in my truck? It seems by turing and counting rotations it would be hard to tell between the 5:89 and 4:89?

HingsingM37 wrote:Ok, so I read the gear ratio info on the "CRUZIN" post. This got me wondering. I always asumed I had the factory military gears. As I never left 3rd gear driving in the backyard before I parked her and began teardown, I never got near 45 let alone 55. Now I did find it odd that when I disassembled my axles the carriers had only nylon locknuts and no lockwashers? I thought nothing of it and figured somebody had been in them before. I did not bother to count the teeth or measure the ring gears.
Today I got to thinking and realized my truck had originally come from Memphis Equipment before its life as a crash/fire rig at Cape May county airport in NJ. I had gotten the original parts manual with the truck. So into the den I went to dig for that book. On the cover it says "highway speed 55MPH". Did all the Memphis reworks have 4:89's I wonder?So now that the axles are together, how do I tell which gear set I have in my truck? It seems by turing and counting rotations it would be hard to tell between the 5:89 and 4:89?

No, Memphis builds don't routinely get 4.89's. All the M37's host a top speed of 55mph on the data plates with 5.83 gearing. If you were driving around the back yard in 3rd gear, 4.89 gearing would be highly unlikely. 55mph top end is very possible on highway with 5.83's & a good engine, not a sustained 55 however. 55 is a great cruise with 4.89's with an intermitent 65 being possible.

Thanks Charles. Gearing has always confused me