Transmissions for dummies?

[ahoke]

New to the auto world and have been curious about the different options for 350 sbc transmission. Have a '70 GMC 3/4 ton I will be restoring once the snow melts and just curious why people swap the th350 out for a 700r4. Been trying to find a useful YouTube video but the search function these days is just overly targeted towards watching trash sponsored videos. The videos I do find are overly technical and glance over the simple aspects. In someone could list a few transmissions with a couple pros/cons would be much appreciated.

In short, I will most likely stick with the th350 that's already in the truck, but for daily driving/long distance trips, what's the ideal transmission? Not looking to win any races but the ability to comfortably cruise at 70mph sounds dreamy.

[dagnabbitt]

Originally Posted by ahoke

New to the auto world and have been curious about the different options for 350 sbc transmission. Have a '70 GMC 3/4 ton I will be restoring once the snow melts and just curious why people swap the th350 out for a 700r4. Been trying to find a useful YouTube video but the search function these days is just overly targeted towards watching trash sponsored videos. The videos I do find are overly technical and glance over the simple aspects. In someone could list a few transmissions with a couple pros/cons would be much appreciated.

In short, I will most likely stick with the th350 that's already in the truck, but for daily driving/long distance trips, what's the ideal transmission? Not looking to win any races but the ability to comfortably cruise at 70mph sounds dreamy.

There's nothing wrong with a TH350. The 700R4 has overdrive though, so it is a good transmission for highway speeds and fuel economy. But it is not suitable for towing, and, some people say, less durable overall. Others would point out that 700R4 failure is due to misuse, but I think it just depends upon what you use your truck for.

[kwmech]

A 3/4 ton with a T350? A little odd but not unheard of. Gear ratio and tire size come into play, and also the type of rear axle. 3.54s can be had for a D60. And of course what engine you have

[ahoke]

I have two 3/4 tons now. Both came stock with a 350 v8 and th350

[HO455]

The T350 3 speed non overdrive very common on later (post 68 as it was new in 69) 1/2 tons.

The T400 3 speed non overdrive was the step up from the 2 speed powerglide in 67 and in later years the heavy duty 3 speed automatic transmission

700R4 was GM's heavy duty 3 speed with overdrive automatic transmission. It was based on the T350. It got a bad reputation as a weak transmission. Some of it deserved (The early units) and some caused by improper operation. Lots of aftermarket support. Set up of the TV cable is critical or the transmission will self destruct quickly.

2004r was the light duty 3 speed with overdrive that came in cars only. It was the transmission installed in the Buick Grand Nationals and as such there is a good aftermarket and they can be modified to handle high powered engines, but have no tolerance for towing trailers so a poor choice for most trucks.

Both the T350 and the T400 can have a Gearvendor overdrive unit bolted to them giving them an overdrive.

I won't go I to the rest of the newer computer controlled transmissions that are out there that people use as I have no personal experience with them.

And if you want more in depth information click the link.

https://en.m.wikipedia.org/wiki/List..._transmissions

And the Gearvendor website.

https://gearvendors.com/index.html

There are lots of threads on all of these transmissions here on the site just do a search for the one your interested in. For example

http://67-72chevytrucks.com/vboard/s...d.php?t=701764

[Accelo]

700R4 was GM's heavy duty 3 speed with overdrive automatic transmission. It was based on the T400.
It based on the THM 350 not the THM 400. Some parts are even interchangeable between the two transmissions. GM gave them both the same torque ratings.

Lots of reasons to chose an Overdrive Transmission. One reason often overlooked it how much quieter it makes the cab. Typically they will reduce the engine rpm by one third.
Cheers

[HO455]

I apologize for any confusion my bad information caused. I have edited the post.