4sp to TH350 procedure - The 1947 - Present Chevrolet & GMC Truck Message Board Network

xtinc · 05-28-2005, 04:43 PM

Couldn't find any info on the 4sp SM420 to Th350 swap in the FAQ index. Anyone else done this swap?

72BLAZERDUDE · 05-28-2005, 08:06 PM

Not to hard a swap. I did it a number of years ago so I will try to remember as much as possible. Yes you will have to get a new drive shaft. Four speed is alot shorter transmission so you will need a shorter driveline for the T350. If you have a one piece driveshaft you might should be able to get it shortened should only need to get a new front yoke welded on. You will probably want to get a low transmission hump from an auto truck so it probably wont have a hole in it.. If you want to use a shifter like a Lokar you will have to put a new hole in the floor. If you use a cable type shifter it is a very small hole for the cable to run through. You will also need a different crossmember for the rear trany mount but the holes should already be there. These are just a few of the basics that I can remember. Ask away as I am sure there alot of things I haven't thought of.

05-28-2005, 08:06 PM	#2
72BLAZERDUDE Registered User Join Date: Jan 2002 Location: WATAUGA,TX Posts: 675	Not to hard a swap. I did it a number of years ago so I will try to remember as much as possible. Yes you will have to get a new drive shaft. Four speed is alot shorter transmission so you will need a shorter driveline for the T350. If you have a one piece driveshaft you might should be able to get it shortened should only need to get a new front yoke welded on. You will probably want to get a low transmission hump from an auto truck so it probably wont have a hole in it.. If you want to use a shifter like a Lokar you will have to put a new hole in the floor. If you use a cable type shifter it is a very small hole for the cable to run through. You will also need a different crossmember for the rear trany mount but the holes should already be there. These are just a few of the basics that I can remember. Ask away as I am sure there alot of things I haven't thought of. __________________ 72 2wd 307/AT/AC/TILT WHEEL 78 JIMMY HIGH SIERRA Last edited by 72BLAZERDUDE; 05-28-2005 at 08:08 PM.

05-28-2005, 04:43 PM	#1
xtinc Registered User Join Date: Dec 2004 Location: Vacaville, CA Posts: 16	Couldn't find any info on the 4sp SM420 to Th350 swap in the FAQ index. Anyone else done this swap?



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