Which is stronger in 4lo, 700r4 or th400?

[5akman]

I commercial fish in Alaska tending nets right off the beach. I currently use a heavily modded M715 as the "tractor" to pull the nets up/down the beach as the tide comes in/out. I'm in need of a second such vehicle for this application and am looking at a 1988 K5 Blazer with low miles and one owner (a woman I work with who used it just for hauling hay to her livestock). It has the 350 TBI with 700R4. In this situation, I'd be using 31 x 1550 x 15" ag lug tires (see pic for similiar style) while in 4Lo. I'm wondering if the 700 is any more bullet proof than say a Th400 when working in 4lo as I'm not opposed to buying/building a 400 if need be.

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[84 M1008]

The TH400 is hands down the best transmission GM ever produced.

 

[Rusty Nail]

There really is no comparison...

Sure as hell not a 700! I think that would be the LAST choice.

Might as well go build ONE turbo 400 and forget about it. Forever.

 

[5akman]

There really is no comparison...

Sure as hell not a 700! I think that would be the LAST choice.

Might as well go build ONE turbo 400 and forget about it. Forever.

I guess I thought maybe with the super low gear ratio in 1st, that the 700 might be stronger when in 1st.

 

[1987 GMC Jimmy]

In the spirit of devil’s advocacy, the ‘88 700R4 is a good one, and if you’re just using it for netting and other small loads, it’d probably do well for you. In fact, if you plan for any highway use, I’d go with the 700R4. If it’s just going to be used strictly in the capacity you mentioned with other local errands peppered in there, the TH400 will be more sensible.

 

[5akman]

In the spirit of devil’s advocacy, the ‘88 700R4 is a good one, and if you’re just using it for netting and other small loads, it’d probably do well for you. In fact, if you plan for any highway use, I’d go with the 700R4. If it’s just going to be used strictly in the capacity you mentioned with other local errands peppered in there, the TH400 will be more sensible.

After the drive from CA to AK, this rig will see about 25 miles of use each summer on the beach only and then sit in storage the rest of the year. I'm thinking Th400 and sell the 7004r

 

[bucket]

One thing to look into is axle ratio. A lot of K5's came with tall 3.08 gearing.

And that's a badass rig you've got there!

 

[5akman]

One thing to look into is axle ratio. A lot of K5's came with tall 3.08 gearing.

And that's a badass rig you've got there!

Yea, those gearing options from the factory suck. I was hoping 4.10's were an option but doesn't look like it and I don't want to have to regear both axles.

 

[5akman]

One thing to look into is axle ratio. A lot of K5's came with tall 3.08 gearing.

And that's a badass rig you've got there!

the M715 has a 351W/C6 in it, converted by the prior owner. He added a Detriot in the back and the 16.5L x 16.1 tires. Its slow but pretty much unstoppable in the sand/marbles at the beach. I rebuilt the Holley 2 barrel this summer and put a new electronic ignition on it. New summer it gets a Edelbrock Thunder AVS and all new brakes as it currently doesn't stop very well!

 

[bucket]

Yea, those gearing options from the factory suck. I was hoping 4.10's were an option but doesn't look like it and I don't want to have to regear both axles.

It could have 3.42 or 3.73, they just weren't quite as common.

 

[1987 GMC Jimmy]

If you can get a picture of the RPO sticker on it, the gear ratio code will be GU*, and you can decode it from there. Another thing to consider is the Gov Lock. My consensus is that it’s fine if you’re not rough with it, but I would imagine you’ll be in plenty more low traction situations than me. Mine’s a 3.42 so there’s hope!

 

[shiftpro]

The TH400 is hands down the best transmission ever produced.

Maybe I fixed it for ya...

 

[Rusty Nail]

In the spirit of devil’s advocacy, the ‘88 700R4 is a good one

Great news!

 

[JoeR Jr]

While the TH400 is much stronger than the 700R4, it matters very little when you are in 4L. With the gear reduction of the transfer case, either trans has an easy walk in the park to move that truck. If you hurt either trans in 4L, something else is really wrong.
Joe

 

[5akman]

While the TH400 is much stronger than the 700R4, it matters very little when you are in 4L. With the gear reduction of the transfer case, either trans has an easy walk in the park to move that truck. If you hurt either trans in 4L, something else is really wrong.
Joe

Thats what I was wondering about and why I asked my question referencing 4Lo usage. I'd love to be able to drive to AK with the overdrive of the 700r4 and then have decent reliability also in 4Lo once I get there.