HBO-G

Hi I need some help with a transmission swap on my 1994 Chevy 1500 4x4. It has a 7.4 454 tbi engine. The trans it has is not put in correctly and I have the offer to buy a 1991 Chevy 1500 with a 350 tbi and a manual transmission. What are the obstacles I’m going to face. Is this swap a good idea? I like driving stick more I can cut holes for the shifter run lines and pedals. I’m just worried about the clutch and flywheel problems do I need to buy a clutch for the 454 or use the 350 clutch I’ve been reading some stuff about flex plate weight and balancing please help I appreciate anything thank you (I’m just a 17 year old car enthusiast)

burnhedge

First things first, you need to make sure your getting a transmission that will hold up behind a 454 and that it comes from another 4x4.

You will need a sm465 (4 speed) or nv4500 (5 speed ) . The lighter 5lm60 or nv3500 can't handle 454 torque especially with a 17 yr old driver. Lol.

Personally I wouldn't worry about the flywheel /clutch. You can buy new quality parts for the 454 for less than $200 rather than reuse 30 yr old parts that likely need replaced anyway.

Things to worry about -
Will your current transfer case work behind the manual (spline count and adapter ) or will you need to swap the TC too.

How does the length of the new trans/tc compare to the old? This may make one drive shaft too long and one one too short. If you swap drive shafts from the donor, do they have the same ujoints and flanges needed?

I'm just curious. Was the 454 swapped into your truck? If so, does it have a 4l60e or 4l80e behind it?

HBO-G

thank you for the help. the truck originally had a 4l60 and the previous owner blew it so decided to take a trans out of a suburban and put it in along with a junkyard 454. Thank you for the advice on some other forum’s people had told me about the nv4500 but said I need to get a different drive shaft

burnhedge

Going from 4l60 to nv4500 is the easiest because they are the same length, but you also need the transfer case because the two trans have different output spline counts.

If the trans from the suburban is a 4l80 then you will have the length issues to deal with, but it has the same spline count as manual transmissions.

HBO-G

Yea the trans and transfer case is from a suburban so it’s a 4l80 but the previous owner didn’t have the wiring harness for it and cut the 4l60 trans plug and was not able to make it work the truck only has second gear and reverse from what Ive read the 4l80 can put up with a 454 how can I get the 4l80 to work in my truck the 4l80 has a computer controlling it ? Or is that just the newer ones do I need to rip out the wiring out of a suburban and wire it up to my truck any answer would help please and thank you

burnhedge

Keeping the 4l80e is definitely the way to go. They are almost bulletproof and if all the work is done but the wiring then no reason not to keep it.

Unfortunately I haven't done this swap so hopefully someone can chime in that can walk you through the wiring.

I'm pretty sure you can buy a adapter harness to make things easy rather than re pinning. You'll also need to know what computer you have and if it needs to be flashed.