Transmission gear ratios

The following are some of the transmissions that I feel are worth considering when performing an engine swap in a M37 or similar vehicle.  This is not meant to be an exhaustive chart and it and the brief descriptions underneath are culled from various sources on the internet.  Please let me know if you find any inaccuracies or have any additions that you think I should make.

  Spicer 3053 16.5" case Spicer 3053A Spicer 3053B SM420 SM465 12"case Clark 280V Clark 280VO 15" case
1st 5.90 6.00 4.5 7.02 6.55 7.48 5.98
2nd 3.10 3.31 2.5 3.57 3.58 4.38 3.50
3rd 1.70 1.89 1.5 1.70 1.57 2.40 1.86
4th 1.00 1.00 1.0 1.00 1.00 1.48 1.00
5th 0.85 0.85 0.75     1.00 .80
rev   5.90       6.30 5.04
torque           330lbft 330lbft
Input           1.5" 1.5"
weight             208lb
  NV4500 Dodge 21" case NV4500 GM 21" case NV5600 Dodge ZF S6-650 6-speed manual (Chevy/Ford)

ZF S542/S547

5-speed manual (Ford)

1st 5.61 6.34 5.63 5.79 5.72
2nd 3.04 3.44 3.38 3.31 2.94
3rd 1.67 1.71 2.04 2.10 1.61
4th 1.00 1.00 1.39 1.31 1
5th 0.73 0.73 1.00 1.00 0.76
6th     0.73 0.76  
rev       5.23  
wieght 200lbs   360lbs 230lbs  

ZF S650: An extremely heavy-duty unit with 6 forward speed. All gears are synchronized. This unit has an aluminum case with integral bell housing, a center support, and rear case. This unit is built in both 2 and 4WD versions. The S650 is found behind diesel engines of 1998 and up Ford Super duty and stripped chassis up to a gross combined weight of 26,000 lbs. The unit weighs in at 230 lbs. A unique feature of this unit is an internal oil pump driven off the front of the countershaft that circulates the lube to a Transmission cooler. An easy way to identify this unit is by the cooling lines mounted to the case as found in automatic transmissions.  Id tags are mounted on the left side of the main case. Only has a PTO port on the right (passenger side)

NV5600:  This very heavy-duty 6 speed is used in heavy-duty Dodge trucks from 1998 on. All forward speeds fully synchronized, this unit has an aluminum bell housing, cast iron case and extension housing, with top mounted shifter.  Available in both 2 and 4WD versions, this unit weighs 360 lbs. The transmission can handle vehicles with a gross combined weight of 26,000 lbs.

NV4500:  5 speed, fully synchronized top loaded heavy-duty transmission. Cast iron case and extension housing with aluminum shift cover. Unit weighs 200 lbs.. Found in GM full size trucks and stripped chassis 92 and up, and in 1994 and up Dodge V8 trucks. There is also a 4500HD model that is used in 1994 and up Dodge trucks behind the V10 diesel engines. This unit MUST use Castrol Syntorque Fluid for lubrication fill.

Information about the Ranger Overdrive that I installed between the Cummins and the stock transmission in my M37 may be found on my Ranger Overdrive page.