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Old 11-03-2014, 03:06 PM
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258 to GM 350 Swap! How Hard?

I just got a 1980 CJ7 with the 258 straight 6 with automatic transmission.1st question can someone tell me what transmission this most likely will be. It's not stamped anywhere. 2nd question the 258 has a blown head gasket. How hard would it be to put a GM 350 in the place of the 258. I already have a fresh 350 sitting on the engine stand. Could someone maybe tell me what all I would need to do to get the 350 to fit. Will the Transmission I have bolt up to the 350 or will I need to replace the Transmission as well. Thanks for any imput.

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Old 11-05-2014, 08:59 AM   #2
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The transmission is normally an A904 if memory serves me right. The GM 350 swap is very popular so parts to do so are fairly easy to get. As for the original transmission, a lot of it depends on the power output of the motor going in as to whether it will hold up or not but we normally recommend using the TH350 and the D300 you already have. If you like you can give me a call or send me a PM and I can get you some pricing on the swap.

Tom Schnarrenberger
4WD Hardware Sales/Jeep Expert
Phone: 1-800-884-1647 x4876
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Old 11-05-2014, 11:33 AM   #3
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Novak has everything you need to do a SBC 350 swap. They even have adapters to use your stock auto trans. I would use a TH350 or TH400. I have been thinking of swapping in a SBC 350, also. Good luck!
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