th 350 to th 400 swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

gregg72340 · 11-21-2010, 01:34 AM

Hi guys just a thought since my 2wd th350 is blown and I cant seem to find a decent used one cheap, what is involved with switching to a TH 400? I know that the driveshaft would be different, I currently have a one piece but have heard that if I do this swap I can use a driveshaft from a 3 speed truck and it would be a bolt in, has anyone else ever heard that one?

Also can anyone think of any other issues I may run into with doin this swap other than moving the crossmember?

Thanks

gregg72340 · 11-22-2010, 05:38 PM

Bump............Not a single person has heard of doing this ever?!?!?!?!?!

Dru · 11-22-2010, 06:41 PM

Shame you didn't live closer, I have a turbo 350 I'd just give you, hate those things with a passion. The 350 to 400 swap should be pretty common.

Driveshaft, and crossmember is really all you have to concern yourself with, the rest is the same. The driveshaft will have to have a turbo 400 yolk on the front, but I dunno about direct swap in lengths. I would be curious about this also, as I need to to do a similar swap myself, but using a Muncie, or a turbo 400 also, these trucks came with long tail 350's.

Your crossmember will only need to be a few inches further back, Id be half tempted to modify the one in place, and extend it, if it could be made to clear the pan. I dunno offhand how it will fit though.

baclay9 · 11-22-2010, 08:12 PM

The bolt holes to move the cross member back are already in the frame.

11-21-2010, 01:34 AM	#1
gregg72340 Registered User Join Date: May 2010 Location: ambler, pa Posts: 325	th 350 to th 400 swap Hi guys just a thought since my 2wd th350 is blown and I cant seem to find a decent used one cheap, what is involved with switching to a TH 400? I know that the driveshaft would be different, I currently have a one piece but have heard that if I do this swap I can use a driveshaft from a 3 speed truck and it would be a bolt in, has anyone else ever heard that one? Also can anyone think of any other issues I may run into with doin this swap other than moving the crossmember? Thanks __________________ Just would like the snow to stop so I can actually work on my truck!!!!!!!!!!!

11-22-2010, 05:38 PM	#2
gregg72340 Registered User Join Date: May 2010 Location: ambler, pa Posts: 325	Re: th 350 to th 400 swap Bump............Not a single person has heard of doing this ever?!?!?!?!?! __________________ Just would like the snow to stop so I can actually work on my truck!!!!!!!!!!!

11-22-2010, 06:41 PM	#3
Dru Registered User Join Date: Oct 2010 Location: Wichita, Ks. Posts: 89	Re: th 350 to th 400 swap Shame you didn't live closer, I have a turbo 350 I'd just give you, hate those things with a passion. The 350 to 400 swap should be pretty common. Driveshaft, and crossmember is really all you have to concern yourself with, the rest is the same. The driveshaft will have to have a turbo 400 yolk on the front, but I dunno about direct swap in lengths. I would be curious about this also, as I need to to do a similar swap myself, but using a Muncie, or a turbo 400 also, these trucks came with long tail 350's. Your crossmember will only need to be a few inches further back, Id be half tempted to modify the one in place, and extend it, if it could be made to clear the pan. I dunno offhand how it will fit though.

11-22-2010, 08:12 PM	#4
baclay9 Registered User Join Date: Apr 2010 Location: Newcastle, OK Posts: 1,344	Re: th 350 to th 400 swap The bolt holes to move the cross member back are already in the frame.



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