Transmission questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jnf2k2 · 11-30-2015, 11:52 AM

Hey everyone,
The transmission on my 76 K10 is going to probably give out any day now and I'm looking for some help on what to replace it with. It's got a TH350 in it and I'm not too keen on rebuilding it since I'd like to have a 4 speed, maybe a 5 speed. Right now it struggles to get up to 45/50.
So basically what would be the best transmission to go with for what I want? How much should I expect to pay, would it be any easy swap, would the transfer case need to be switched out as well, etc. Also somewhere down the road I'd like to put a 454 in it, it's got a 350 now, and what transmission would be fine for both.
Any help or advice anyone could give is highly appreciated.

**Gregski** · 12-30-2015, 02:57 PM

ok, I'll comment since this post is still fairly current, how about the Tremec T-5? Now I don't know much about them other than they came on the early 80's Ford Mustangs 5.0 and are good up to 300 lb-ft of torque (which may be not enough) but either way I think the T-5 is worthy of at least a discussion.

68c10owner · 12-30-2015, 03:35 PM

The T5 also came in v6 and 305v8 camaros and some S10 models. It is not a very strong transmission. It certainly would not last long in a heavy 4wd with much abuse. You may want t consider a late model truck 5spd. You need to find something that will bt up or adapt to your transfer case.

Tom · 12-30-2015, 03:40 PM

We just had a huge thread about the T5 not being a good choice for 1/2ton+ trucks.

If your truck struggles to get to 45-50mph,I highly doubt it will stay at that speed in an overdrive gear. Fix the engine.

jnf2k2 · 12-30-2015, 04:11 PM

Thanks for the replys everyone. Forgot about this post since I never got a response.

I've given it alot of thought and research and I'll most likely go with a TH400. I dont have much need for an overdrive gear as I mostly use the truck for hunting at the moment and am not as concerned about gas mileage. Also it seems like it should be an easier swap that way.

I've been looking at picking up one from Monster Transmission in Brooksville, Fl since they're local. Anyone have any thoughts or experiences with them?

68c10owner · 12-30-2015, 04:20 PM

Quote:

Originally Posted by jnf2k2

Thanks for the replys everyone. Forgot about this post since I never got a response.

I've given it alot of thought and research and I'll most likely go with a TH400. I dont have much need for an overdrive gear as I mostly use the truck for hunting at the moment and am not as concerned about gas mileage. Also it seems like it should be an easier swap that way.

I've been looking at picking up one from Monster Transmission in Brooksville, Fl since they're local. Anyone have any thoughts or experiences with them?

No experience with them but a google search would probably find some reviews.

Notihng wrong with rebuilding the th350 you already have. Going to a th400 would require a different driveshaft and yoke and if its a pretty stock 350 engine it will rob more power. TH400`s take more power to spin than a TH350.

KrazyRay · 12-30-2015, 04:54 PM

You will need the transmission/transfer case adapter that is specific to a 400/203.

*gmachinz* · 12-30-2015, 05:41 PM

Trans cross members are also different I believe. No reason to swap trans from a 350 to a 400. I had the TH350 in my k10 Shortbox rebuilt earlier this year. I went with a transgo shift improver kit stage 2, kevlar overhaul kit, extra 1-2 and 2-3 clutch packs, swapped out the stock overhaul misc. retaining snap rings for heat treated industrial versions, retained the stock converter and bought a 2-extra quart TCI aluminum pan. All of this set me back about $625 including synthetic ATF Mobil 1 fluid.

And it was WAY easier to lower the trans with t-case bolted to it. I used a transmission jack and secured both with chains. The t-case is heavier than that trans and it will try to roll sideways as you lower it down/out.

barry1982 · 12-30-2015, 11:27 PM

Just my opinion... but I would stick with the turbo 350 as well. You are already set up for it....
Don't get me wrong... the TH400 is a strong towing transmission, but in my experience , the turbo 400 does not take well to the "R an D" that we often do with 4 x 4's in mud holes. I "fixed" a couple this way, and an old tranny repair man shared this info with me.

11-30-2015, 11:52 AM	#1
jnf2k2 Registered User Join Date: May 2015 Location: Tampa, Fl Posts: 21	Transmission questions Hey everyone, The transmission on my 76 K10 is going to probably give out any day now and I'm looking for some help on what to replace it with. It's got a TH350 in it and I'm not too keen on rebuilding it since I'd like to have a 4 speed, maybe a 5 speed. Right now it struggles to get up to 45/50. So basically what would be the best transmission to go with for what I want? How much should I expect to pay, would it be any easy swap, would the transfer case need to be switched out as well, etc. Also somewhere down the road I'd like to put a 454 in it, it's got a 350 now, and what transmission would be fine for both. Any help or advice anyone could give is highly appreciated.

12-30-2015, 02:57 PM	#2
Gregski Post Whore Join Date: Aug 2014 Location: Sacramento, CA Posts: 10,884	Re: Transmission questions ok, I'll comment since this post is still fairly current, how about the Tremec T-5? Now I don't know much about them other than they came on the early 80's Ford Mustangs 5.0 and are good up to 300 lb-ft of torque (which may be not enough) but either way I think the T-5 is worthy of at least a discussion. Attached Images

12-30-2015, 03:35 PM	#3
68c10owner Registered User Join Date: Oct 2003 Location: Carmichael, California Posts: 3,011	Re: Transmission questions The T5 also came in v6 and 305v8 camaros and some S10 models. It is not a very strong transmission. It certainly would not last long in a heavy 4wd with much abuse. You may want t consider a late model truck 5spd. You need to find something that will bt up or adapt to your transfer case. __________________ Anthony

12-30-2015, 03:40 PM	#4
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,760	Re: Transmission questions We just had a huge thread about the T5 not being a good choice for 1/2ton+ trucks. If your truck struggles to get to 45-50mph,I highly doubt it will stay at that speed in an overdrive gear. Fix the engine. __________________ -78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me.

12-30-2015, 04:11 PM	#5
jnf2k2 Registered User Join Date: May 2015 Location: Tampa, Fl Posts: 21	Re: Transmission questions Thanks for the replys everyone. Forgot about this post since I never got a response. I've given it alot of thought and research and I'll most likely go with a TH400. I dont have much need for an overdrive gear as I mostly use the truck for hunting at the moment and am not as concerned about gas mileage. Also it seems like it should be an easier swap that way. I've been looking at picking up one from Monster Transmission in Brooksville, Fl since they're local. Anyone have any thoughts or experiences with them?

12-30-2015, 04:54 PM	#7
KrazyRay Registered User Join Date: Jun 2009 Location: Oroville, CA Posts: 4,827	Re: Transmission questions You will need the transmission/transfer case adapter that is specific to a 400/203.

12-30-2015, 05:41 PM	#8
gmachinz Account Suspended Join Date: Jun 2011 Location: Des Moines, IA. Posts: 4,143	Re: Transmission questions Trans cross members are also different I believe. No reason to swap trans from a 350 to a 400. I had the TH350 in my k10 Shortbox rebuilt earlier this year. I went with a transgo shift improver kit stage 2, kevlar overhaul kit, extra 1-2 and 2-3 clutch packs, swapped out the stock overhaul misc. retaining snap rings for heat treated industrial versions, retained the stock converter and bought a 2-extra quart TCI aluminum pan. All of this set me back about $625 including synthetic ATF Mobil 1 fluid. And it was WAY easier to lower the trans with t-case bolted to it. I used a transmission jack and secured both with chains. The t-case is heavier than that trans and it will try to roll sideways as you lower it down/out.

12-30-2015, 11:27 PM	#9
barry1982 Registered User Join Date: Oct 2015 Location: Waskatenau, Alberta Posts: 259	Re: Transmission questions Just my opinion... but I would stick with the turbo 350 as well. You are already set up for it.... Don't get me wrong... the TH400 is a strong towing transmission, but in my experience , the turbo 400 does not take well to the "R an D" that we often do with 4 x 4's in mud holes. I "fixed" a couple this way, and an old tranny repair man shared this info with me.



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