350

[GM_Zach]

Hello my name is Zach, I’m going to be doing a complete restoration on my 1986 Sierra Classic k1500 4x4. It currently has a whimpy 305 and a 3 speed with a granny gear. I want this to be my daily driver as it has sentimental meaning. I have been building a 350 with vortec heads. My main question is which transmission will give me daily driving use and better mpg for cross country driving. I’m not a millionaire but I’m not broke. I do want to do all the work myself I don’t care how much time it takes. Anything Helps thanks! Willing to deal with electrical work as long as it’s not too big of a mountain.

 

[Shorty81]

Welcome Zach. I prefer the SM465 that you currently have. Bullet proof tranny. But I understand you want overdrive. You will need a modern 5 speed transmission. Plenty of guys here to help you along.

 

[82sbshortbed]

A solid th400?

 

[animal]

 

[Bextreme04]

Since its already a manual, you can convert to an NV4500 from a newer chevy or dodge. 700R4 would also work OK for what you are saying you use it for and want to convert to an automatic. 4L80E would be the heavy duty automatic route.

 

[GM_Zach]

What are your guy’s opinion on gear vendors. I would personally love to keep in manual. But my main goal is street and daily use. So even if I have to switch to automatic I want to cruise at 75+ no problem. Overdrive is a must. I will be using it to drive coast to coast. Thanks for all the support !

 

[Babs]

 

[Corvette Ed]

Welcome aboard.

 

[1973c10]

Welcome

 

[Grit dog]

What are your guy’s opinion on gear vendors. I would personally love to keep in manual. But my main goal is street and daily use. So even if I have to switch to automatic I want to cruise at 75+ no problem. Overdrive is a must. I will be using it to drive coast to coast. Thanks for all the support !

What is your gearing and tire size or what's it going to be?
I'd say the vast majority of setups would benefit from overdrive for over the road, say up to 80mph cruising speeds for hours on end. If you got big tires and high gears, it may be of lesser value. Actually with the 4 speed, 3.08s and 33s might act like overdrive.
Otherwise, NV4500 drop in would be my preference for keeping manual and OD.

Use one of those online rpm/speed/gear ratio calculators. And then plug in your fixed parameters (IE, you aren't re-gearing and know you're running 31" tires) and the variable parameters. There are a multitude of ways/combinations to achieve desirable rpms at a given speed on the highway.

 

[SquareRoot]

Gear vendors will cost ya about $3200. I studied this every which way. Since it's already a manual trans I would go with a NV4500 from AA. Less money, warranty, overdrive and bulletproof.

I recently swapped from a th400 to nv4500 and increased my mileage by about 20%. And its FUN to drive.

 

[SquareRoot]

Double post.

 

[mcarlo86]

What is your gearing and tire size or what's it going to be?
I'd say the vast majority of setups would benefit from overdrive for over the road, say up to 80mph cruising speeds for hours on end. If you got big tires and high gears, it may be of lesser value. Actually with the 4 speed, 3.08s and 33s might act like overdrive.
Otherwise, NV4500 drop in would be my preference for keeping manual and OD.

Use one of those online rpm/speed/gear ratio calculators. And then plug in your fixed parameters (IE, you aren't re-gearing and know you're running 31" tires) and the variable parameters. There are a multitude of ways/combinations to achieve desirable rpms at a given speed on the highway.

Gear ratio and tire size are important factors. If you have 3.08's in it and plan on running bigger tires, then OD might actually hurt you. I'd say put 3.73's in it if it doesn't already have them and run 31" tires with a NV4500. If it has 3.08 or 3.42's, and you don't want to do a gear swap, then just run the SM465.

 

[Rusty Nail]

My first thought was 700-R4 for ease of installation and serviceability? You could simply duplicate an existing factory setup with great ease.

Then my second thought involved vortex heads and "dude may want that later model trans" but then I started wondering about lift and tire size and I saw somebody say "gear ratio" and then I was like " man , **** all that new stuff anyways. I don't support them later model stuffs.

We started this post with ease of installation and serviceability..im stuck at 700-R4 for you although tire size and lift and gear ratio are too important to overlook.

Need more information @OP.

 

[Grit dog]

Gear vendors will cost ya about $3200. I studied this every which way. Since it's already a manual trans I would go with a NV4500 from AA. Less money, warranty, overdrive and bulletproof.

I recently swapped from a th400 to nv4500 and increased my mileage by about 20%. And its FUN to drive.

For light duty use, if you find a Getrag 5LM60/NV3500 (basically the same trans), it could be a very economical option. They had a bad rap, as I recall (pre internet days and the word got out, lol) but I had 2 of them, both in 1990 1/2 tons. One went about 250k miles when I lost track of the truck and it was still kicking and another I ran up to about 100k when I sold it. Should be about half price of a NV4500. Not near as heavy duty, but if you find a good one, it will work, shift more friendly than the iron case 4500 and cost half as much or less.

 

[RedBeard_83]

Welcome from Florida