Transmissions for towing

[flintspear]

I'm running a k3500 with a NV4500, 4.10's. Will be towing a 10k+ horse trailer in the (hopefully) not too distant future. The wide shifts in the 4500 are a problem, esp going from 3rd to 4th in hilly terrain. Any suggestions on a swap or mod? I'd like to keep the rpms around 2000-2200. I know I can go to a under/over drive - ie, GV or USGEAR. Any other options anybody knows of? NV5600 swap? The truck handles a lighter trailer ok, but the wide shifts are still a bit of a problem at around 6500 trailer weight.

Also, have done a bit of reading on the NV4500. Apparently this tranny comes in two forms, one a HD in the Dodge Cummins, with heavier input/output shafts. Anybody know if the Chev tx is a HD version. My truck is rated at just under 10k tow weight in the manual. I might have to go a bit heavier than that. I trashed one of these not long ago - my own fault- put in GL-5 lube. Don't do it. But learned something. Apparently 4th gear is the strongest in this tx. How about an overdrive running in 4th? That might be a bit stronger than straight 5th. I don't expect to run this whole rig (about 16 k pounds) faster than about 60. That would keep the rpms in a reasonable range. BTW just ran this truck from Vail to Denver without a downshift (over Vail pass at 10,500), a nice run with about 14-15 mpg at 65-70. Cool temps definitely help.

I love my truck.

98 cc k3500. KE filter, bone stock from there.

[moedog]

You can upgrade to the 6spd. it will fit but is much larger and heavy. As you probably know, stock 6.5s dont like mountains, altitude and heavy weights. I have found people who swear by the splitters but all fight over which one, gear vendors or US gear. they are both a pricy option, around 2500 for the part plus labor. I know the GV unit is complete and the eaiser of the two to install.
thats about all i can offer

[MTTwister]

Hey "flinty.." let me recommend Gauges - EGT, Boost, Tranny temp. Then research the Cheap TCC lockup, and homemade boost fooler. Synthetics in Diffs and Auto Trans are a good idea also ( I went Amsoil- via Greg L - advertiser on this site). The search feature on the above will give you some pro's and con's... My horse hauling days are over ( I think) but at least our passes top out at @ 7,000 ft, not your really thin air.. Good Luck.

[big61fourby]

Somebody correct me if I'm wrong, but I believe an NV5600 will help wide shift range of the 4500. It basically has an extra gear between 1st and direct, which shortens the jump between gears. A little searching could probably find a ratio chart for both?

As stated above, the 5600 is big, and quite a bit more so than a 4500. It would involve moving crossmembers, and possibly a body lift just to clear the tranny? I really don't know how adaptable they are to 6.5 TD (and t-case?). Seems like last time I checked, they were still kinda pricy too. If the price were about the same, I think I'd probably look at a GV--you get 10 speeds instead of 6, and you get double overdrive, which should help out with fuel mileage, esp. empty. Just a thought.

[ak46champ]

I am getting ready to do a bunch of towing myself. I just purchased the GV overdrive with much hesitation. But it was the best purchase I think I could have made. I plan on keeping the truck, that is why I decided to buy it, all said and done it cost me $2700. My RPM's droped from 2350 at 70mph down to 1550. I was absolutly amazed. I haven't had the chance to check fuel mileage yet for long distance, I know for in and around I now get about 16-17 mpg and that has been for the summer with temps 80-100 degrees. K3500 6.5TD CC Long box SRW