Help with gear transmission advice

[HammerWerf]

Frank,
The 082 indicated the axle was manufactured in 1982

the 70HD is the axle is the Dana model 70 heavy duty. Really good axle.

The other numbers you found I don't recognize right off hand.

HammerWerf

[HammerWerf]

Frank,

The other numbers I did not recognize, I think is the "Bill of Material" number. This number is important as the way of identifying the parts that will fit that axle. Apparently, not all parts fit all axles.

HammerWerf

[Frank M. Hardcastle II]

Frank,

The other numbers I did not recognize, I think is the "Bill of Material" number. This number is important as the way of identifying the parts that will fit that axle. Apparently, not all parts fit all axles.

HammerWerf

Thanks Guys! I found the gear ratio. I feel like such an idiot. I've looked at all the descriptive stickers I could find. Drivers door, glove box, under the hood on the wheel well and radiator support(?) at least 3 times now. I must be going blind or something. Found it on the drivers wheel well under the hood. 4.56. I found a ratio calculator on the net that shows at 3200 r.p.m.'s I would be traveling about 65 m.p.h. with a 4.56 rear end ratio. Well thats what my speedometer shows. Now I know. Next question is how much farther do I want to go? I don't want to lose too much power but sure would like to be in that 1800 r.p.m. area for maximum fuel mileage. I was thinking about 3.73 or 3.42. A local gear shop said they could change out the gear for $650 if I only moved up one step (4.11?). The caculator I found indicates only a 7 m.p.h. increase at the same 3200 r.p.m. I'd really like to increase my top speed to 90+ m.p.h. but don't know how this will impact my SM465 4 speed Muncie with Granny Low. I'd still like to be able to take off from a stop without using granny low every time.

[DmaxMaverick]

The ONLY way you are going to be able to get your RPM's below 2K at 65 is:

Increase gear ratio to 3.42/3.73 with an OD 5 or 6 speed or the gear change with oversize tires. A 5 speed OD will lose the granny low.

Increase gear ratio to 4.11 with OD tranny and oversize tires.

You can play with the combinations, and adding an aux. OD gearbox will increase your chances of getting into the RPM range you want. Also, oversize tires, while they do increase your final drive ratio, have more parasitic loss than gears, requiring more power/fuel to turn them.

[arveetek]

I don't want to lose too much power but sure would like to be in that 1800 r.p.m. area for maximum fuel mileage. I was thinking about 3.73 or 3.42. A local gear shop said they could change out the gear for $650 if I only moved up one step (4.11?). The caculator I found indicates only a 7 m.p.h. increase at the same 3200 r.p.m. I'd really like to increase my top speed to 90+ m.p.h. but don't know how this will impact my SM465 4 speed Muncie with Granny Low. I'd still like to be able to take off from a stop without using granny low every time.

My suggestion would be to go the 4.11 gears and install an overdrive transmission. That would give you better cruising rpm and still keep the power level there. I'm really happy with my 4.10 gears, 30" tires, and overdrive tranny. It's a good combination for power and highway driving.

Casey