TH350 TH400 Swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

65chevysub · 11-18-2014, 11:19 PM

How hard would it be to swap out my bad TH350 for a TH400?, and what year would I use that hopefully isn't computerized? My truck is a 1965 Suburban, with a 283, '72 Tilt Column for the TH350. I don't want to use a 700R4 or 4L60E if I don't have to as I just use my truck to drive around town, and am on an extremely tight budget.

**Captainfab** · 11-19-2014, 01:21 AM

Most any year TH400 will work. There are no electronic versions. I would suggest the short shaft TH400, but you will still have to move the crossmember and have your driveshaft shortened. The TH400's came with either a slip yoke, or a fixed yoke. If you get one with the fixed yoke, you will need either a special slip yoke, or have a slip yoke added to your driveshaft. This is assuming you have a one piece driveshaft.

65chevysub · 11-19-2014, 08:58 AM

Thanks Captain. I still have my 2 piece driveshaft. I believe my mount has been moved when I had the TH350 put in after the Powerglide was removed, and the driveshaft modified a little. Should I stay with the 2 piece driveshaft? I tried a 1 piece several years ago without success. Haven't had any issues with it except the carrier bearing mount broke at the spot welds. I drilled out the welds, and bolted it together and it's still holding. That was about 10 years ago.

**Captainfab** · 11-20-2014, 01:33 AM

It sounds like you have the whimpy light duty carrier bearing. I would go with a single driveshaft in a Suburban. That's what I have in mine. If you had a long bed pickup or the longer 1 ton panel, then a 2 piece driveshaft with the HD carrier bearing would be better.

65chevysub · 11-20-2014, 08:52 AM

It's the original driveshaft it came with. The one thing I, and other members can't figure out, is why some of the Subs came with 1 piece and some with 2 piece driveshafts. My shaft is ok. I just had a problem with the welds on the bearing. I found a driveshaft shop in the Phoenix area, and will check with them about a 1 piece in the future when I get the new trans. Thanks for your help.

65chevysub · 12-01-2014, 11:58 AM

Just a question about the swap. Should I just stay with a TH350, just a little newer one? The pan on the one I have now says it's a 1978 model, but the pan that could have been replaced.

11-18-2014, 11:19 PM	#1
65chevysub Registered User Join Date: Feb 2013 Location: Cottonwood, Arizona Posts: 1,382	TH350 TH400 Swap How hard would it be to swap out my bad TH350 for a TH400?, and what year would I use that hopefully isn't computerized? My truck is a 1965 Suburban, with a 283, '72 Tilt Column for the TH350. I don't want to use a 700R4 or 4L60E if I don't have to as I just use my truck to drive around town, and am on an extremely tight budget.

11-19-2014, 01:21 AM	#2
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,252	Re: TH350 TH400 Swap Most any year TH400 will work. There are no electronic versions. I would suggest the short shaft TH400, but you will still have to move the crossmember and have your driveshaft shortened. The TH400's came with either a slip yoke, or a fixed yoke. If you get one with the fixed yoke, you will need either a special slip yoke, or have a slip yoke added to your driveshaft. This is assuming you have a one piece driveshaft. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

11-19-2014, 08:58 AM	#3
65chevysub Registered User Join Date: Feb 2013 Location: Cottonwood, Arizona Posts: 1,382	Re: TH350 TH400 Swap Thanks Captain. I still have my 2 piece driveshaft. I believe my mount has been moved when I had the TH350 put in after the Powerglide was removed, and the driveshaft modified a little. Should I stay with the 2 piece driveshaft? I tried a 1 piece several years ago without success. Haven't had any issues with it except the carrier bearing mount broke at the spot welds. I drilled out the welds, and bolted it together and it's still holding. That was about 10 years ago.

11-20-2014, 01:33 AM	#4
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,252	Re: TH350 TH400 Swap It sounds like you have the whimpy light duty carrier bearing. I would go with a single driveshaft in a Suburban. That's what I have in mine. If you had a long bed pickup or the longer 1 ton panel, then a 2 piece driveshaft with the HD carrier bearing would be better. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

11-20-2014, 08:52 AM	#5
65chevysub Registered User Join Date: Feb 2013 Location: Cottonwood, Arizona Posts: 1,382	Re: TH350 TH400 Swap It's the original driveshaft it came with. The one thing I, and other members can't figure out, is why some of the Subs came with 1 piece and some with 2 piece driveshafts. My shaft is ok. I just had a problem with the welds on the bearing. I found a driveshaft shop in the Phoenix area, and will check with them about a 1 piece in the future when I get the new trans. Thanks for your help.

12-01-2014, 11:58 AM	#6
65chevysub Registered User Join Date: Feb 2013 Location: Cottonwood, Arizona Posts: 1,382	Re: TH350 TH400 Swap Just a question about the swap. Should I just stay with a TH350, just a little newer one? The pan on the one I have now says it's a 1978 model, but the pan that could have been replaced.



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