TH-350 to TH-400, different trans mount? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

'70 C/10 SS500 · 08-28-2003, 03:20 PM

(I know this is in drivetrain, but need some replies fast!)

I'm in the process of installing my Caddy 500/TH-400 into my previously 292 I6/TH-350 '70 C/10. The trans mount from the caddy cross member doesn't look like it'll work with my truck cross member. For reference, the motor/ trans. came out of a '76 Coupe Deville. The tranny is a long tail shaft BOP TH-400.

Questions:
1. Is there any difference between tranny mounts for a 350 vs. a 400?
2. Can I just unbolt my 350 mount, put it on the 400, and relocate the crossmember?
3. What tranny mount do I need to use?

crazy longhorn · 08-28-2003, 08:20 PM

I think you will find the mount to be "universal", but you will need to relocate the crossmember. There are 3 different lenghts on the 400 turbo, & mounts are position different for each. Try this link on lenghts.... http://www.tciauto.com/tech_info/trans_dims.htm I need to rephrase that, the aftermarket mounts are slotted, & should fit either a 350 t or a 400 t. good luck,crazyL

Longhorn Man · 08-28-2003, 10:29 PM

I dunno Al, the one on my Caddy 400 is totally wierd.
I have no answer for the question though.

crazy longhorn · 08-28-2003, 11:15 PM

Its been a while since i have been under a caddy.....I take your word for that "odd" mount on the Caddy ,Andy

as far as the truck mounts go, from the factory the 350 & 400 turbos had a different bolt pattern on the trans. The last couple mounts I got (aftermarket), that were for the truck had the holes slotted so they would fit either a 350 or 400 turbo. If you follow the link in to TCI, it will show the bolt spacing for the mount.....the 350 turbo took the same mount (factory) as the 3 & 4 spd stick trannies(saginaw, muncie). The 400 turbo had a wider bolt pattern for the mount.....aftermarket was a "universal fit"(something done right to keep the parts guys from cursing!) LOL! OOps!....I havent tangled with that longtail 400 turbo, & I do see that it shows a different pattern yet on the trans! I ran the D tail on the trans that was behind the Olds & the caddy......it looks like that 13" tail had one odd ball mount setup

crazyL

Longhorn Man · 08-28-2003, 11:49 PM

Yup. It's something like 4 or 5 inches bolt to bolt.
That's one reason I have a Pontiac tranny in mine.

08-28-2003, 03:20 PM	#1
'70 C/10 SS500 Registered User Join Date: Jun 2003 Location: Chandler, AZ Posts: 130	TH-350 to TH-400, different trans mount? (I know this is in drivetrain, but need some replies fast!) I'm in the process of installing my Caddy 500/TH-400 into my previously 292 I6/TH-350 '70 C/10. The trans mount from the caddy cross member doesn't look like it'll work with my truck cross member. For reference, the motor/ trans. came out of a '76 Coupe Deville. The tranny is a long tail shaft BOP TH-400. Questions: 1. Is there any difference between tranny mounts for a 350 vs. a 400? 2. Can I just unbolt my 350 mount, put it on the 400, and relocate the crossmember? 3. What tranny mount do I need to use?

08-28-2003, 08:20 PM	#2
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	I think you will find the mount to be "universal", but you will need to relocate the crossmember. There are 3 different lenghts on the 400 turbo, & mounts are position different for each. Try this link on lenghts.... http://www.tciauto.com/tech_info/trans_dims.htm I need to rephrase that, the aftermarket mounts are slotted, & should fit either a 350 t or a 400 t. good luck,crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... Last edited by crazy longhorn; 08-28-2003 at 08:23 PM.

08-28-2003, 11:15 PM	#4
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	Its been a while since i have been under a caddy.....I take your word for that "odd" mount on the Caddy ,Andy as far as the truck mounts go, from the factory the 350 & 400 turbos had a different bolt pattern on the trans. The last couple mounts I got (aftermarket), that were for the truck had the holes slotted so they would fit either a 350 or 400 turbo. If you follow the link in to TCI, it will show the bolt spacing for the mount.....the 350 turbo took the same mount (factory) as the 3 & 4 spd stick trannies(saginaw, muncie). The 400 turbo had a wider bolt pattern for the mount.....aftermarket was a "universal fit"(something done right to keep the parts guys from cursing!) LOL! OOps!....I havent tangled with that longtail 400 turbo, & I do see that it shows a different pattern yet on the trans! I ran the D tail on the trans that was behind the Olds & the caddy......it looks like that 13" tail had one odd ball mount setup crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... Last edited by crazy longhorn; 08-28-2003 at 11:22 PM.

08-28-2003, 10:29 PM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I dunno Al, the one on my Caddy 400 is totally wierd. I have no answer for the question though.

08-28-2003, 11:49 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Yup. It's something like 4 or 5 inches bolt to bolt. That's one reason I have a Pontiac tranny in mine.



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