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Which transmission in front of a doubler? TH400, SM465 or NV4500?

rompinstompinmudmonkey

rompinstompinmudmonkey

1/2 ton status
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So I have a dilemma. I have 3 transmissions in my posession and I can't decide which one to run. Before I get too far ahead of myself, here's a little background.

The truck in question is my 77 K5. (See sig) It currently has a 383, SM465, (10 spline) and a 205. This has been a very solid and reliable setup so far, with no major problems.

I have a 203/205 doubler (32 spline) with triple sticks sitting on the shelf ready to install behind whatever trans I decide to go with.


Trans #1 TH400.
Pros: This trans was mated to the 203 so it has the correct length output shaft and the adapter to mate the 400 to the 203. I also have the torque converter and a winters shifter already.
Cons: The trans is a core and needs a full rebuild. I also need to get a cooler, lines, a flex plate, and may possibly run a manual valve body or a reverse manual valve body.

Trans #2 SM465
Pros: This is a super reliable transmission that I have had in the truck for 10 years. It shifts a little sloppy, but has taken some serious abuse and has never left me stranded
Cons: It has a 10 spline output, so I would either need to swap the main shaft, or find a 32 spline 465. I would also like to switch to a hydraulic clutch. My main complaint with my current setup is that I can't shift when I'm in the mud. I wind up the motor too fast in 2nd gear and don't have a bunch of top end speed, but lose too much wheel speed if I try to grab 3rd and sometimes bog the motor.

Trans #3 NV4500
Pros: Trans has a 32 spline output, so I could tap the face of the 203 and bolt it right up. Also 5th gear is appealing because this truck will now see more road time than it did in AZ. I already rebuilt the NV4500 that's behind my cummins so I have one under my belt and the special tools to rebuild one too
Cons: I would more than likely have the same shifting issues in the mud with the NV4500 as I currently do. I would also need a bell housing and the rest of the parts to convert to a hydraulic clutch.


So what say the brotherhood? I have spent countless hours going over each scenario in my head and I can't seem to make up my mind.
 
in your case, a stout gutted #1... RMVB FTW....
 
Is mud all you do? Go with a manual, and just add more horsepower in front of it.

Martin
 
Mud isn't all I do, it's just a majority of what's available around here. I ran quite a few rocks and trails while in AZ. My wife's whole family lives there and I would like to take the blazer back once in awhile for vacation. I also plan on wheeling the black hills, and would like to throw Moab in the mix too. For right now the main purpose of the truck will be using it around the farm. Fixing fence, checking/ fixing irrigation pivots, chasing cows, and playing in mud and snow.
 
Keep the manual then. Unless it's whole life is in a mud pit, there is no reason to suffer an automatic the rest of the time.

Martin
 
I would go 4L80E over all of them, but if a decent amount of road manners is required a NV4500 would be a good trade over the 4L80E. Both of them would be pricey though. I personally find the 465 to be a huge pos, terrible gear split, and a shift pattern wider than what it takes to row a boat. Plus overall they can not take as large of amount of input torque vs your other options, but thats just how I have seen it personally. The 400 is stout as can be, and is a decent choice, but using a stick opens up the front of the radiator a bit more because of the lack of cooler. And one less thing to constantly leak as sticks dont leak near as often in my experience.

I personally dont like MVB, I prefer modding mine to hold any gear, but still upshift when I would like it to. With the manual valve bodies, its basically a stick without the extra pedal, and I have no use for sticks except holding down dumpsters.

But, to make a better informed choice, it would be nice to know your axle gears and tire size, as OD might not be necessary if you have a high enough gear and tire size.
 
I've got 4.10's and 38" Boggers. I plan on mounting a set of military 37's on some spare rims to use for for when it spends more time on roads.

I absolutely don't want a 4l80e.
 
Then a TH400 or the 465 will work for you fine. You wont need OD with that size tires and that tall of gearing. A 465 will get you better low, and have more takeoff power as its gearing is better than the TH400.
 
My opinion is go with the th400. You don't need the overdrive with your gear/tire size, and you can shift in the mud. You can put a higher stall 'converter in too.
 
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