He said its a 3/4 ton... so I was assuming it had some flavor of 14 bolt rear end and heavier duty suspension. Either way, it isn't a 1500. You could get a TH350 or 700R4 on 3/4 and 1 ton Chevy trucks and Suburbans since at least the 70's. I had a high gross weight camper special 74' C20 pickup that had a 350/TH350 combo and 4.56 rear gears from the factory. There are many 8 lug C/K 20's and 30's out there with 350/400/454's and a 700R4 from the factory and 14B full or semi-float rear ends. It wasn't until 1991 that choosing a 4-speed automatic RPO in 3/4 and 1-ton chevys got you a 4L80. From the 84 to 91 you could only get a TH400 or 700R4 and the 700R4 was standard on the 6.2 Diesels.
Can a Th700r4 be used for towing?
- Thread starter scornedlotus
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Supercharged111
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His isn't an 8 lug 2500 though, it's a 6 lug.
scornedlotus
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Thank you everyone who's responded and game your inputs. I have taken what everyone has given me into consideration. The conclusion I have come to is no matter what I'm extremely happy with the trade a 600k subi for a 172k obs. I will be rebuilding the silverado and use it for towing light duty for a while well I look for a heavier duty truck. Then hopefully find a collector to take in the beauty I have found, so an other who appreciates the classics can enjoy.
1989GMCSIERRA
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At the weight you’re planning on hauling that whole truck isn’t gonna do the job. 11,500 pounds is a lot to ask out of a 90s Chevy. And no I dont care how tough someone think the truck is at those weights you’re in “I need/should have a diesel for this” territory. Forget swapping engines rebuilding xyz. Sell that Chevy and get something newer in a diesel if you plan on towing a lot but I’d stay away from small blocks at that tow weight. And for f sake don’t believe these commercials of towing a 11,000 pounds with a half ton today.
Where did he say that? He said 3/4 ton in the first post... your post was #10 talking about it being 6 lug? I can't find him saying it is 6 lug anywhere. No pics of it in the thread, so no idea what rear axle it has or what the actual rating is?
Supercharged111
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OP has a 700R4, it's a 6 lug. 8 lug and it'd have a TH400.
As I've stated multiple times... that's just not true. You could optionally select an overdrive transmission with several different drivetrain packages and have 8 lug axles.
https://www.gm.com/content/dam/comp...its/chevrolet-trucks/1988-Chevrolet-Truck.pdf
Go to the power teams section for 3/4 ton and above starting on page 22. MX0 is a 700R4, MX1 is TH400. Those were the only two auto transmission options GM offered in 1988.
You will notice that you could not actually get a 3/4 ton truck in 1988 with a 350/TH400. That combo only came in C/K 3500. They only came with a 700R4.. period. You COULD get a TH400 in a 3/4 ton, but it only came paired with a V6 or 305.
Supercharged111
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You sure you don't have that backwards? Why TF would you put a TH400 behind a V6 and not a 350?
Doesn't change the fact that this truck is not capable of pulling an 11k 5th wheel. PERIOD. He could get by with 11k on a flatbed, but no way in hell with that aero penalty would this truck ever dream of pulling a house down the road.
If it's backwards, then the 1 Ton could only ever come with a 700R4 in ALL powertrain combinations, which is obviously not the case.
The answer to your question is emissions. The smaller engines were able to pass the fuel efficiency numbers without needing the overdrive. That was the major driving factor behind the 4L80E being developed, but it didn't come out for another 3 years. The 1 tons had a GVWR of at least 8600lbs, so they could get away with the higher emissions numbers and lower fuel economy of turning the higher freeway RPM's.
I agree on the towing. The main weak point here no matter how the rest of the vehicle is equipped is the 700R4. Even though an 11k 5th wheel is probably only ~7800lbs in the normal dry weight that he would be pulling it at, it is still too much. That trans is going to cook or blow up fast even if he keeps it in 3rd and puts a big external cooler on it. Another concern would be the frame and suspension ability to carry the 5th wheel load in the bed. It's going to be ~2200lbs of weight on the ball, which is going to be more than the rated payload. He would need airbags at a minimum and even then it likely wouldn't be legal.
All of this is still just speculation(except the trans stuff) because we still don't have pics of the actual truck and/or pics of the SPID sheet and GVWR/GCWR sticker
That "8-lug" "6-lug" question was on my mind too.
In the FSM it appeared the 700R4 was offered behind the diesel, which I would only expect (?) to be offered in something with 8 lugs.
In the FSM it appeared the 700R4 was offered behind the diesel, which I would only expect (?) to be offered in something with 8 lugs.
