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Hey, guys. Long time viewer, first time poster, so be gentle. Haha. I recently bought a '67 short stepside c10 and am in the process of freshening up the drivetrain. We (dad and I) just rebuilt the engine which is now a mild Vortec 350. (325-350 hp?) We are trying to decide on what transmission to follow it up with. As of right now it has the stock sm420 granny tranny. I like the durability of it, and the character it gives to the truck, but damn is it a pain sometimes, haha. My main interest of upgrading the trans is for the option of overdrive. I'm going to be finishing up high school here soon, then off to college. I plan to keep this old girl, and fix her up along the way. However, I'm going to be traveling on the freeway much more often, and overdrive would be a godsend. Not only that, but a much smoother, cleaner, and firmer transmission would liven up the truck. I haven't pulled the diff cover to see, but based on math the rear end is somewhere in the low 3's. (3.0-3.5:1) It's a slightly lowered 2wd, 26.5" outside tire diameter. I'd like your guy's opinions on what to do. Having a part time job, and in high school, i'm of course on a budget. I'm hoping to only spend a max of $2000-$3000 on this ENTIRE conversion, but all suggestions are welcome. Now the hard part, Auto vs Manual. I love the feel and control of a manual, plus it keeps you occupied, but from what I've seen, the conversion would be much more expensive. I'm looking right now in either a 700r4, t5/t56, or a TKO 500. Originally I was leaning towards the TKO, but budget wise I am being forced back to the r4. I've been trying looking at built up 700r4's online, but the reviews are so incredibly varied, I don't quite know what to do. Or, is it even worth the cost for the gas savings and driveability. My goal for this is a sport truck, fast and fun, but with the option of the very rare tow included. Again any suggestions would be awesome, thanks.

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well first you have to decide what you want auto or man, but for the gears if your going to be doing alot of highway driving you dont want to go to low but if your planning on sporting and by that you mean burning alittle tire and running red light to red light and a tow here or there you dont want to high. my personal opinon for the best all around is 3.43's for auto and 3.73 for manual but thats me. if you go auto a 7004 isnt bad i know in my area the local trannsmisson shop keeps a rebuilt one on the shelf at all times and he sells them rebuilt uninstalled for about 1000-1200 but you got to figure what you want.

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200r4

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yep - if you want an auto, 700 or 200 are fine options. If you prefer to row your own, then a T5 sounds like your price range. If you plan to get on it occasionally, pass on the T5, even a WC T5, and go to the 700 or 200 to stay lower cost. Any T56 or TKO is gonna run you right to your limit $-wise pretty quickly.

If I misunderstood - and you AREN'T gonna lay into it now and again, here's a thread on swapping a T5 (into a 66, but same process applies). Even if not - several tips on how and mfgr poc info, etc inside. http://67-72chevytrucks.com/vboard/s...d.php?t=482069


If you have no preference of manual over auto - then I'd probably swap over to an automatic. Only keep it manual if you WANT a stick.
Nice looking truck you have there! Good luck!

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well I've been down that road to many times.You have to ask your self who else is going to want to drive your clean hot rod.Most old people would rather get in it and go.Your girl friend or wife will want to drive it once in awhile.And if you ever driven a big truck with a stick you problem would not be asking us this question.Now days the stick is being put to rest.Look in Most of your full size trucks there auto's.

Another thing to ask your self resale Most people would rather have a overdrive with a auto and willing to pay for it.

One good reason i can state here in calif the 1990- 93 Honda Accord was a wonderful looking car.Resale even today is really high at 4200-5000 for a Auto.Now the same car with a stick and lesser miles is only worth 1500.00

something about having to change a clutch then pulling the hole trans and having it rebuilt or replaced

the 200R4 and the 700R4 are very good trans and it will give you a good resale.

I know moist of us say it But I've seen over and over again money gets tight we sale are hot rods to pay the bills.Get the bang out of the buck.

Here is one other thing you might want to think about they make a 8 speed trans in the new Corvettes.Now if you have a 200R4 or 700R4 you can have a 8 speed in it and it will jerk your teeth out.it will cost you some money.But it will give you a 4.90 Gear first gear and a 290 final gear

and its a Gear Vender

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Welcome from Central Florida! I love the style of the 67...just looks cool.
I prefere an automatic so I would probably go the R4 route.
Nice truck BTW

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My choice would be the R4 in either the 200 or 700 variant.

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If you wanna get on it, I'd stick with a manual. If you're looking for MPGs, don't do anything, Because dropping a few grand for a handful of mpgs will take a very long time to recoup. And like stsalvage said, with how things are nowadays, selling is a strong possibility, and you won't recoup the money if you sell it in a year or two. Financially, it'd be better to put that $3k into a gas fund.

Also, manual, auto, overdrive or gearing, the best gas saver you'll ever acquire is a disciplined right foot. I'd stick with the SM420, raise the gears, but if you said low 3s, I wouldn't go higher than a 3.43, if you go any higher like 2.xx you'd have no pep in your step, only benefit if you did like 80% of your driving highway.

I know, I'm practical, it's a drag :D

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Slush-box tranny's are for little girly men. Strong muscular men drive manual transmissions! :lol: With that being said- stay clear of the T5. You're still in your teens which means you ARE going to trash through the gears! No offense- just sayin'. The T5 and even stock T56 can't take much abuse. Keeping the budget low and factoring in a reasonable amount of dependability....I would either throw-down and get the TKO, Richmond or Kiesler 5-speed or get your self a reman'd MY6, which is essentially an A883 (think BB 'Cuda) with a GM bolt pattern and input, with the exception that 4th gear is a .88 overdrive cog.
If you wimp out and swap for an auto- go with the 700-R4, the lower first gear will get you off the line quicker and help with the whole "occasional towing" thing.

Send us some update when you can!

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Ya for autos, go with the 700r4, overdrive, and the lowest 1st gear of either a 350 or 400. Think it's a 3:1 when the other two are 2 something.

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Thanks guys for your input. I'm trying to make this decision and put it into action before spring break so i'll update you with my final decision in a week or so. I do agree with MrSchaeferPants on the fact that it would take a long time to earn back what money I sink into this solely in gas savings, and Dingfodgy on "Strong muscular men drive manual transmissions!" :metal:. Say if I was to stick with the sm420, is there anyway to smooth it out? It's very jerky, rocks back and forth in gear, sometimes a PITA to shift, etc. This is another reason I was looking into upgrading. I understand it's just the nature of it, but any tips for improvement?
:burnout:

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There are still rebuild kits for the SM420, but with a non-synchro 1st. and reverse gear it's still gonna be a granny-tranny. An NP465 is an improvement but not enough to justify the swap. Your best bet is to go ahead and put in the 5-speed or OD automatic (whatever you decide to do). If you can find a Muncie M21 or M22 for cheap- that would be a good 4-speed, but with a 1:1 fourth gear, you won't gain any mileage over the SM420.

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If you have to have overdrive you might consider a nv4500.... its cheaper than everything besides a T5 and more bulletproof than a SM465 and doesn't shift too bad....


OR..... keep your SM420 and put in a set of 3.08 axle gears.... then you wouldn't be turning too much on the highway....


I'm a 700R4 hater.... I killed countless 700r4s before I did my SM465 swap .... but then again I have a 11:1 compression 383 that makes mountains of torque from 3000-5000RPM :metal::metal:



the SM465 and SM420 are almost the same.... here is how to fix the sloppy shifter..... http://www.pirate4x4.com/tech/billav...465/index.html

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Alright guys, thanks again. I'm sticking with the sm420, at least for now, and am definitely gonna try out that sloppy shifter fix, thanks americanmusc1e. Planning on ordering the few rest of the items needed to swap the engine (plugs, wires, clutch kit, etc) tonight or tomorrow morning. I'm stuck between either a Hays Super Truck or the popular Centerforce DF. If I go with the Centerforce, I also have to get the TO Bearing and pilot bushing, so it definitely has a heftier price tag. Opinions? For this size motor, is it worth it to go for the Centerforce? Or should I skip them all together and go for a cheaper kit like a ZOOM?

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Centerforce hands down... Only clutches I will use anymore.

Gary

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Center force is pricey....but its the only clutch that I have not been able to tear up in my old truck;) crazyl

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How about keep the trans you have an add a gear vendors overdrive unit?

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I thought about doing that as well, but for relatively the same price, I could get a much smoother, quicker transmission, and not have to deal with the jerky granny gears. However, it would be a much quicker and easier overdrive install... Just seems pretty spendy for what it is.

And for the rest of you I did go ahead and order the Centerforce DF Clutch. :metal:

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I have a Ram musclecar series 11" on mine and I think i hurt it for the first time a while back running the truck hard..... I launched hard revved the 383 to 6000 and slammed it into second and let go of the clutch and the RPMs shot up... I thought I had missed a gear, but it was in gear when I checked.

the ram musclecar series is almost $100 cheaper than the centerforce dual friction.... and your 350 probably would not hurt it. But if you have the money and you wanna be absolutely sure... do the centerforce.


here is the clutch i used... I don't know if yours would be the same though because I have a late-model (89) SM465 with an aftermarket flywheel.
http://www.summitracing.com/parts/RAM-92762/

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Haha, you're making me wish I had gone for that Stroker kit. I was looking into that clutch too, and you're right, my 350 probably wouldn't phase it, but I went ahead and got the centerforce anyways. Might as well put the best on it now when I've got it out and not have to worry about it later...

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Well, when I was 18, I loved that old stroker... but now that I am getting older and wiser I'm starting to realize that my 5000lb truck will never be as fast as these new cars I was trying to keep up with.

I realized that I enjoy driving my truck a lot, and a motor that gets 8mpg on premium gasoline just isn't that fun to cruise in.

So now I'm lowering the compression and changing the cam to better suit my driving style.



I still have to race though.... I'm building a Raptor 660r drag bike bit by bit.... around here fourwheelers are about the cheapest racing thrill I can get, and a lot of fun.....

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-
Here's another option...

http://67-72chevytrucks.com/vboard/s...d.php?t=475370

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