I'm looking at starting a NBS SUV with Manual transmission project (2000-2006 Tahoe/Yukon/escalade). The T-56 will fit with almost no modification, but I want to be able to tow if needed. I am wanting to use a truck transmission, the nv4500 or even better maybe the ZF-6. The Nv4500 is only on the HDs because it requires a 2" body lift to fit. The ZF-6 supposedly takes a 3" body lift to fit. I drive my daily like I'm in an autocross, and really enjoy my cornering. I never go off road, and we don't have snow and rain only a few days out of the year. I DO NOT want to use the factory 2" body mounts like the HD to make it fit, especially when I will lower the rear to level or do a minimal suspension drop. I know that's the easy way, but I'm thinking I want to cut out some of the trans tunnel/hump to make it fit so the body can stay at the regular 1/2 ton height, and then having it redone to allow room.

I am hoping to only swap the trans for the time being. At best I will be able to remove the transmission, but any fab work that's needed, I won't be able to get done where I do mechanics (there is no welding done there), so this would have to be outsourced. Most likely I will remove the auto trans, and interior that would be in the way. Then towing it to a shop to cut out, and rework.

I have no clue how to weld, how difficult this would be, but more importantly what I could expect from a shop. Can anyone help me get a better idea of how difficult this would be for a fab shop? How much it should roughly cost? What problems we might come across? Or anything else you care to bring up about this? Would this require removing the engine or any other parts (wiring, lines)? I need to try to see how difficult it is, but I might be able to cut out what is needed, and then only have a new cover made and welded on. Thank you.

 

Are you 100% sure on the NV4500 requiring a lift? They were used in GMT400's across the board in same applications that used lighter duty transmissions. I don't know the specifics on how they fit/don't fit a GMT800 truck but you may want to check other sources before writing off the NV4500.

Richard

 

From what I understand there is some "slight manipulation" required to make it fit. I understand that to mean "hit it with a hammer", but most of you all don't dumb it down enough for me. The ZF-6 is supposedly even bigger, and a hammer probably wouldn't cut it. Just trying to understand what my options are. I'm finding rebuilt zf-6s cheaper than an nv4500. The ZF-6 wouldn't be needed unless I go FI, WAY down the road, just trying to plan farther ahead if its only going to be minimal increase to do it the first time.

 

 

I'm seeing the 4500 for about $1300->$2k (if getting cryod parts). I found 2 companies selling the GM 2wd ZF6 trans for under $2K. (+about $500 core on both, that I would have to pay).

 

I cut the transmission tunnel a lot in my 67 Chevelle to install a Tremec TKO 600. I used pop rivets to attach the sheet metal to close up the tunnel and then sealed it with calking.

 

NV4500 should fit as-is. the 2" lift was needed to fit the Allison & ZF-S6-650. only reason the 4500 was only in the HD is because the 6.0 exceeded the torque rating for the 3500.
there's also a thread on here about doing a custom full-console shift linkage, too, so you ain't gotta remove it for a jump seat.

 

Zebra is correct the NV4500 fits without any lift body or suspension. If you have a manual trans truck already the factory trans crossmember will even work unmodified.

 

just in case you're still considering this...
if for some reason, you still want to run a t56 in a full-size SUV, try & find one from a GTO or Gen1 CTS-V (M12 RPO). they had the deeper gearing. you'll still want a 4.30 or 4.56 rear end (as opposed to a 4.88 or 5.13 with the camaro [MM6] ratios).
...and i ain't seen nobody try it, but you could also look into the feasibility of a tr6060 from a G8 GXP or Chevy SS... they had a longitudinal setup with about the same ratios as the M12.

if sticking with a truck trans that won't shift as good but will better-handle the weight, i learned during my nv4500 swap that there were 3 different interchangeable top covers (lids) for it. the 01-06 GM lid (GMT800) is slightly taller than the 95-00 (GMT400) version to accommodate the factory HD body lift... so for putting it in a NBS 1/2 ton, use the GMT400 lid to buy a little room... and look for a 96+ transmission (for the internal slave setup & correct bolt pattern).