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royale 75

identifying 400 vs 350 turbo

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I am taking a 455 from a 73 Pontiac grandville and putting it into my 75 Olds delta 88. How can I determine what tranny is in the olds vs the Pontiac? I assume the 455 only came bolted to a 400 but wonder if my 350 4 bbl olds delta could have a factory 400. The olds has only 80k orig miles and tranny works great so I'm tempted to keep it versus the pontiac which seems to work fine other than it doesn't downshift upon acceleration as it should (works fine manually and shifts solid. Pontiac tranny is alledgedly rebuilt but who knows. Any advice?

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The TH400 used a different type slip yoke than the others. Here's a site for Olds transmissions. I think Olds normally coupled 455 with TH400 trans. I had a 455 Olds engine coupled to a TH350. It will work ok, but won't stand up to much hot rodding.

http://www.442.com/oldsfaq/oftrn.htm#TRAN%20Auto%20Transmission%20Identification

Others have done the same. BOP (Buick, Olds, Pontiac) share a common transmission bolt pattern so one should fit the other. If you do use a TH350, I would get a separate trans cooler. They are cheap and easy to install, the trans shop I use swears by them.

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A quick way to check is the 350 has a shift kick down cable, the 400 does not have a cable, you can see the cable by looking under the hood near the firewall heading down to the transmission on the passenger side of the car.

Looking at the transmission pan under the car the 350 will be square shaped with a corner cut off. The 400 pan will be a free form shape with lots of curves. Henry

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