tranny swap questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

firefighterpickett · 10-14-2004, 09:15 PM

Has anyone switched a th-350 for a th-400? I just finished going from gas to diesel and now want to swap my tranny, I belive there is only a small size difference, so really only moving the crossmember and possibly new driveshaft

454K5 · 10-14-2004, 10:37 PM

they also use a different kickdown (detent). the th350 has a cable, the th400 has an electric solenoid. and the dipstick tubes are also different. other than that, it's a direct swap, other than...like you already said, move the crossmember, and modify the driveshaft.

firefighterpickett · 10-15-2004, 02:24 PM

great, thanx for the help, always nice to confirm what your thinking before tearing things up.

*1972C10* · 10-15-2004, 06:39 PM

The output shaft is larger on a TH-400 therefore you will need a new Yoke Shortened Driveshaft unless you have a 9" TH-350 And depening on what yoke you get you could need a 30 dollar conversion u joint Let me know what year and i can tell you what P/N If its pre 80 its a presicion 447

firefighterpickett · 10-17-2004, 04:50 PM

it is a pre 80 so the pn would apply, thanx

10-14-2004, 09:15 PM	#1
firefighterpickett Registered User Join Date: Aug 2004 Location: colorado Posts: 24	tranny swap questions Has anyone switched a th-350 for a th-400? I just finished going from gas to diesel and now want to swap my tranny, I belive there is only a small size difference, so really only moving the crossmember and possibly new driveshaft __________________ Remember the fallen. 9-11-01 76 K5 4X4 custom roll cage/soft-top, turbo 400 & np 208 http://www.youtube.com/sp2fraggle http://www.oilfieldtrash.biz

10-15-2004, 02:24 PM	#3
firefighterpickett Registered User Join Date: Aug 2004 Location: colorado Posts: 24	great, thanx for the help, always nice to confirm what your thinking before tearing things up. __________________ Remember the fallen. 9-11-01 76 K5 4X4 custom roll cage/soft-top, turbo 400 & np 208 http://www.youtube.com/sp2fraggle http://www.oilfieldtrash.biz

10-17-2004, 04:50 PM	#5
firefighterpickett Registered User Join Date: Aug 2004 Location: colorado Posts: 24	it is a pre 80 so the pn would apply, thanx __________________ Remember the fallen. 9-11-01 76 K5 4X4 custom roll cage/soft-top, turbo 400 & np 208 http://www.youtube.com/sp2fraggle http://www.oilfieldtrash.biz

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10-14-2004, 10:37 PM	#2
454K5 Registered User Join Date: Jan 2004 Location: Ft. Worth, TX Posts: 19	they also use a different kickdown (detent). the th350 has a cable, the th400 has an electric solenoid. and the dipstick tubes are also different. other than that, it's a direct swap, other than...like you already said, move the crossmember, and modify the driveshaft.

10-15-2004, 06:39 PM	#4
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	The output shaft is larger on a TH-400 therefore you will need a new Yoke Shortened Driveshaft unless you have a 9" TH-350 And depening on what yoke you get you could need a 30 dollar conversion u joint Let me know what year and i can tell you what P/N If its pre 80 its a presicion 447



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