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So heres the deal, I'm the young owner of a 1985 El Camino SS Choo Choo and I'm looking to over time turn it into a high performance street car. I've replaced the 305 with an overbore 350 from a 1969 Chevorlet Camero. It creates plenty of power, but I have an issue with the gearing of the 3-speed automatic. Can anyone give me a suggestion for a high performance automatic transmission upgrade that will fit my car?

Thanks in advance for all your help forum. :)
 

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i just put a shift kit in my th350 b&m to be exact supposed to chip tires going into 2nd but havent tried it yet i think alot of people go to a 700r4 its a 4 speed or 3 speed with overdrive...whatever haha the th350 are pretty good but the th400 are stronger if i had the $ i would go with a th400 with a shift kit
 

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VINTAGE MOTORHEAD
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Welcome from sunny Florida. There sre some keen trans gurus that lurk around herr. I am sure one will come along to assist you.
Good luck. Enjoy the site.
 

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Overdrive

I like the overdrive. Two reasons: Quicker 1st gear and lower rpms at cruise. A 700r4 is fine, but a 200-4r is really a better transmission in my opinion because of its even gearing. 2.74 first gear as opposed to a TH350's 2.52 first gear. Some modifications to the driveshaft and crossmember have to be done of course, but you can buy a strong 200-4r (or 700r4) from aftermarket manufacturers like California Performance Transmissions or resellers like Jegs or Summit. Expect to spend $1200-up for a strengthened one. A strong TH350 or TH400 would probably be half as much.
 

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So heres the deal, I'm the young owner of a 1985 El Camino SS Choo Choo and I'm looking to over time turn it into a high performance street car. I've replaced the 305 with an overbore 350 from a 1969 Chevorlet Camero. It creates plenty of power, but I have an issue with the gearing of the 3-speed automatic. Can anyone give me a suggestion for a high performance automatic transmission upgrade that will fit my car?

Thanks in advance for all your help forum. :)
I'm assuming you have a TH350?

What rpm/mph range do you not like with the current gearing of your transmission?

If you don't like the gearing off the line, then you probably need to get rid of those 3.08 gears in your rear axle (Just Guessing).

A TH350 trans is perfect for your combo if you want to stay with a three speed trans. Especially if you want a "high performane street car." TH350's can be built very strong. A TH400 would be complete overkill for anything under 700 hp, IMO. They're great transmissions, I love mine, but they weigh about 20-30 lbs more than a TH350 and require about 30 more HP to operate them over a TH350.

Mario
 

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...but a 200-4r is really a better transmission in my opinion because of its even gearing. 2.74 first gear as opposed to a TH350's 2.52 first gear. Some modifications to the driveshaft and crossmember have to be done of course...
If you currently have a TH200 or 200C, the upgrade to a 200-4R is pretty easy. The first three gears of the 200-4R are identical to the TH200s. Also, overall case length is the same so you can re-use the driveshaft you already have. You will have to change crossmember, as tail mounting points are different. Think ahead and maybe splurge on a crossmember that will allow for dual exhaust for when you get to that point in your build.

200-4Rs can be built to handle power, fairly easily. Just ask and Turbo Grand National owner. 4Rs came stock on their rides and their rides can easily do 10s. I'm currently trying to complete my own rebuild of a 200-4R and replacement of my TH200C, but progress has been slow lately. Good luck!
 
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