The G56 is a good transmission in spite of the lower OD ratio IMHO. TDR had one with 80K miles on it taken to a major transmission rebuiler to be tore down and looked at and then compared to the NV5600. When the transmission was taken apart they found several heavy duty features found in Eaton or Spicer Medium Duty Truck transmissions that were not found in the NV5600 The G56 has been used in MB Medium Duty trucks for quite awhile before Dodge started using it in the HD 2500 and 3500 trucks. The early problem found with the G56 was they were first shipped to the dealers with out enough oil in the them and they were burning up and stopping procduction. Once that was corrected they put them back into production. I have had a ZF5 in the 90 F250 before and I like the G56 better and inspite of the lower geared OD I am still able to get over 20 mpg when crusing on the high way better than I got with the 99 2500 Dodge with the automatic and 3:54 which got good mileage.
How about them ol' 4 speeds. Look how many of those are still on the road in original form....I had one and it would pull anything, maybe not fast but it would pull! waytogo
Okay, so it sound like we have just three major choices for for six speeds. We have the Ford ZF series, the NV5600 and the new Dodge G56. I don't think that the Ford tranny is bad, if fact quite the oppisite. Ford does seem to have a great tranny it is just the 6.0 that is the problem for these trucks. The NV5600 was an awesome tranny. No doubt about it. I currently have the G56 in my 1 ton dually, crew cab, 4x4. My only gripe with the tranny is that even with the 3.73 gears in the pumpkins I wish I had a seventh gear. I have hauled 25,000 pounds with the truck and did not need a lower gear. But, when I get out on the highway I wish I had another gear for cruising. At 65 mph the engine is running at 2000 rpm's. Perhaps this is not too bad for either the Ford or the Chevy due to their higher reving engines. But the Cummins redlines at 3200 rpm's. For me the fuel mileage drops dramaticaly if I run the engine past the 2000 rpm's. I have yet to see a need for a 4.10 ratio in my truck.
Another vote for the NV-5600. The one in my truck started to shift kinda hard back last fall when the weather was getting cold. Simply changed the trans oil with the high quality, full-synthetic oil of my choice (make sure you get the right stuff as the 5600 is awful picky about the correct oil) and it now shifts as smooth as any other truck tranny out there.waytogo
Amsoil Synthetic Manual Syncromesh Transmission Fluid. http://www.amsoil.com/StoreFront/mtf.aspx First time I've ever used an Amsoil product and I can honestly report a definite shift-quality increase over the factory fill.
So far I like my six banger with the six speed manual and six wheels. Pulled my 5er up and over Cheat Mtn West Virginia like it was nothing. The route has a 9% grade with 15, 20 , and 30 MPH curves. I cant wait to do it again.waytogo
The one thing that is nice about the G-56 is its aluminium case. It runs about 20 degrees cooler than the NV 5600. These tranny's are all made and designed by the same supplier, Magna, which bought out New Venture Gear. I used to do business with NVG\Magna. We manufactured gears for them.
NV5600 is the best, why dodge ever got away from that is beyond me. Their new manual is a piece of junk, the gears are way to close together. The ford 6-spd is a close second, and gm pulls in 3rd place. The best i personally owned was a 00 F-250 T444E with a 6-spd 3.73.
Dodge got a way from the NV5600 because it is not longer made so Dodge had to go somewhere else to find a replacement. I have put over 45K on my G56 and it has been a very good tranmission.
