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Best trans replacement for a 1966 Tempest

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Hello there, I'm looking for advice for a replacement transmission for my 1966 Tempest 4 door. It's got the original 326 and 2 speed automatic(st300.) I'm on a budget and can't afford to have a bunch of things fabricated, so ease of transition is key. I've heard a turbo 350 would be a good swap because the cross member would not need to be moved and I wouldn't need to have a driveshaft made. Any advice or experience that could be shared by the community would be greatly appreciated. The 2 speed is shot and I really don't want to rebuild it. Thanks. 

Edited by SVEtempest
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Any new or rebuilt transmission will probably run around $1500-1800 (assuming you don't have a case to start with). I see a couple of choices - a 350 turbo or a 200 4R turbo. Depends on how much freeway driving you do or your desire for overdrive. The 200 4R case is the almost the same size as the 350 case but it has overdrive in it, so it can help with mileage a bit. However, the 200 4R cases are a little harder to find than a 350 or 700 R4 case. The 200 4R is the only GM overdrive transmission that fits the Buick-Olds-Pontiac engine bolt pattern. The 700 R4 is Chevy all the way and requires an adaptor kit.

The tailshaft of the 200 4R is about .5" longer than a 350. So you might need to move or adjust your rear cross member some.

The 200 4R uses a TV cable. The 350TH uses vacuum and a kick down cable. So different set--ups you need to pay attention to. The 200 4R uses a lock-up torque convertor, the 350 does not.

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