M1008 Gearing or Transmisson

[sporanox]

I drive about 60 miles to work on the interstate. Would it be better to swap transmissions or change the gearing for highway travel?

 

[porkysplace]

I would say a overdrive transmission swap would be best overall , you would still have low end power and better highway speed . Since the 6.2 is lacking power to start with you would gain speed at the top but lose power at the bottom.

 

[Bob H]

I know a M1010 with a Gear Vendors overdrive unit. He's pretty happy with it.

 

[sporanox]

Gear Vendors

I know a M1010 with a Gear Vendors overdrive unit. He's pretty happy with it.

Ouch, Those units are like $3000.

 

[Keith_J]

A 4L80e transmission with the controller is about the same, once you factor in the transmission mounting with transfer case adapter. And all the other problems. But it is better than the GV unit as the 4L80e has a lockup torque converter, eliminating converter slippage so you do not need additional transmission fluid cooling. The GV can increase slippage in the converter, this heats the oil as it is lost power.

If you don't want electronics and won't be using the vehicle for heavy towing, the 700R4 transmission works. It also gives a lower first gear and a taller overdrive, again with lockup torque converter.

 

[GPrez]

Ouch, Those units are like $3000.

Worth every penny in my opinion. Very easy to install and works like a charm. I can cruise 70mph at 2700 rpm, and retain all the benefits of the turbo 400 and 4.56 gear ratio.

 

[Recovry4x4]

Any reasonably rebuilt 700R4 can handle all the power the 6.2 makes even in a heavy truck. I feel that the 700 gearing is an excellent match for the anemic 6.2.

 

[nyoffroad]

Any reasonably rebuilt 700R4 can handle all the power the 6.2 makes even in a heavy truck. I feel that the 700 gearing is an excellent match for the anemic 6.2.

Same here! I'm very happy with my 700R4 conversion and it cost ALOT LESS than $3000! I bet I only have $1000 into it and that includes the rebuild and a new frt shaft. BTW I tow a single place car hauler fairly often and plow snow in the winter and never had a problem.

 

[tequilaiam]

You could try a ranger overdrive and 4 speed.
http://www.advanceadapters.com/tech-vault/ranger-overdrive/

The ranger OD is half the price of the GV unit and muncie 4-speeds are real cheap used (paid $50 for mine off craigslist). You may be able to find a corresponding T-case adapter to keep existing drive shafts.

It's something on my wish list.

 

[Recovry4x4]

You could try a ranger overdrive and 4 speed.
http://www.advanceadapters.com/tech-vault/ranger-overdrive/

The ranger OD is half the price of the GV unit and muncie 4-speeds are real cheap used (paid $50 for mine off craigslist). You may be able to find a corresponding T-case adapter to keep existing drive shafts.

It's something on my wish list.

If you don't mind shaking hands with a shifter, this is a viable alternative. I'll be doing the swap this month in my project truck. The SM465 trans are out there with the long adapter and 32 spline output shaft to use your existing transfer case. The ranger adds 7 1/2" to the trans assy so you will have to shorten the rear and lengthen the front driveshafts. There some nuances with pedal assemblies as well. I plan on covering the details in a thread once mine is done. My parts gathering is complete except driveshafts so once I start I hope to work right through to completion.

 

[tequilaiam]

Then maybe you can use the original adapter behind the TH400?

I'm not sure which year but at some point GM made the bellhousing+tranny+adapter all the same length across the different options. When I did my conversion I took the longer adapter and bellhousing from a chevy gasser and it went right in. If there was an auto that was 7 1/2" longer than the SM465+bellhousing (or very close) you could just use the OEM adapter for that.

Looking here: http://www.novak-adapt.com/knowledge/th350.htm

it appears the TH350 is about 5.2" longer than a 465+bellhousing. So in theory you could use the ranger, 465 and the TH350 adapter and your t-case is now 0.2 inches further back which you can take up wtih the slip yolks. That's assuming a TH350 was available in a 4x4. If not, the same still applies wtih the TH400 but you're off 2" rather than 0.2 but that still might be doable with the slip yolks.

 

[Recovry4x4]

For the most part, you can swap assemblies without changing driveshafts. The 400/208 and 700R4/208 combo works out the same as they absorbed the difference in the adapter. Unfortunately you can't mix match adapters, they are specific for the trans and transfer. Can't bolt a 350 adapter to the back of an SM465. The ranger bolts in between the bellhousing and the transmission so no matter what combo you use, it gets moved back 7 1/2".

 

[truck1]

I run 2310 rpm at 70 mph with my GV OD.

 

[HillbillyWizard]

There is no one right answer to this question. I get asked this one a lot and for good reason. In your case I'd lean towards what most are recommending which is a transmission solution.
700R4 - good option, probably the lowest cost but not for high power
TH400 with gear vendor type unit - easy install, downside is cost and Driveshaft mods
4L80E - excellent trans but needs computer

If you need some prices on takeouts or cores, we have all the above transmissions in stock.

 

[tequilaiam]

For the most part, you can swap assemblies without changing driveshafts. The 400/208 and 700R4/208 combo works out the same as they absorbed the difference in the adapter. Unfortunately you can't mix match adapters, they are specific for the trans and transfer. Can't bolt a 350 adapter to the back of an SM465. The ranger bolts in between the bellhousing and the transmission so no matter what combo you use, it gets moved back 7 1/2".

Good to know! I thought all the GM stuff of the era was available in the 32 spline (or whatever it is) output shaft and could be mix-n-matched.

Now you may as well get that big lift kit since you're getting new driveshafts

 

[Iceman3005]

I have done several 700r4 swaps into these trucks, just about ready to start another one. look for the post and pics in cucv "hot rod and modification". I will try to be a lot more detailed with parts, pics, and specs, then in the previous post I have done for these swaps.

 

[Bob H]

A lift and 37" humvee tires can get the highway speed up.