IV Gen drivetrain in III Gen truck

**Z28dryva** · 02-09-2013, 07:10 PM

I have my dream truck but I would like to do away with the weak 5.3/4l60 that comes in my 05 Z71. In it's place, I would like to swap a late model 6.2/6l90e, PCM and wiring harness into the truck and have all the stock gauges and BCM work correctly. I would also like to explore the options of running another T case and possibly maintaining the ability to have push button 4X4 (auto mode can be done away with). I have heard that such an undertaking would require splicing the new PCM to the old one to allow the gauges to work properly, however, I have seen from looking through this forum that the late model PCM could be modified to run the older model gauges (or at least in an F body). Any info about this swap would be appreciated.

Before anyone says it, no, I'm not going with a late model truck that has such things installed from the factory. The body style I have is the style I've always wanted and will be staying with. Just trying to modernize it to get the most out of the older body style with updated drivetrain options

**2002ssslp** · 02-10-2013, 08:16 AM

I thought the PCM connectors were the same and that it would just need to be reprogrammed. I could be wrong.

**Z28dryva** · 02-10-2013, 01:31 PM

Aside from the cam sensor and knock sensors being in a different places as well as the reluctor for the crank sensor having a different tooth count, there are no differences in the engines as far as electronics is concerned. The problem is the PCM houses the fly by wire system as well as the extensive communication process required between the engine and tranny with a 6l90e operating system. That's really the main concern I have at the moment. It has to have that computer to operate the tranny but that computer might conflict with the older computer system in other parts of the vehicle such as the BCM and the gauges.

**Firebirdjones** · 02-11-2013, 10:32 AM

Trade it in for a newer truck

Had to say it....

Sounds like a tall order. Probably do-able but alot of hassle and money. Why not mod the current 5.3? The 4L60's can be beefed to take the abuse so that's not much concern. 5.3's can be pretty strong with the right components thrown at it.

**Z28dryva** · 02-11-2013, 03:59 PM

Originally Posted by Firebirdjones

Trade it in for a newer truck

Had to say it....

Sounds like a tall order. Probably do-able but alot of hassle and money. Why not mod the current 5.3? The 4L60's can be beefed to take the abuse so that's not much concern. 5.3's can be pretty strong with the right components thrown at it.

My list of reasoning is extensive but I'll narrow it down to a few points. 1, the old 5.3 is old school as hell. It can't accommodate the newer more efficient heads and the older ones can't even handle LS1 heads because of the bore size. I just don't like having to pull the intake to change the knock sensors which are quite problematic and it's a big ole clunky iron block. 2, the 4l60e isn't worth the chewing gum and bailing wire it's made out of. It's barely adequate for a semi modded F body and absolute junk in the trucks. There are plenty of street trucks around here in Oklahoma and they're constantly having tranny issues. Not to mention they're ridiculously geared 4 speeds with a massive gap between 1 and 2 that makes it a dog off the line and terrible at towing if you want to keep your gas mileage gears. If you go lower, the OD gear isn't high enough to make much difference and you have your engine howling like a wolf at high speeds. Not to say the 6l90 is a more reliable transmission but if it is built correctly and has a tuner with the proper understanding of it's operation working on it, it can be a pretty good tranny. 3, this is up for speculation, but I've heard the newer PCM's are a lot more capable than the older ones and are a lot faster as well.

If I become too impatient with all the tedious thing s involved with this swap, I might just consider throwing a Dmax/Allison combo in it

**Firebirdjones** · 02-11-2013, 04:30 PM

So you bought a truck with a drivetrain that you absolutely hate? Wow!

You are getting ready to sink a bunch of money into a truck that was already expensive, and in the end won't be worth 1/4th of what you've spent when it's finished.

Yeah, you need to trade that thing in and start with a platform you would be happier with....

**Z28dryva** · 02-11-2013, 04:42 PM

Originally Posted by Firebirdjones

So you bought a truck with a drivetrain that you absolutely hate? Wow!

You are getting ready to sink a bunch of money into a truck that was already expensive, and in the end won't be worth 1/4th of what you've spent when it's finished.

Yeah, you need to trade that thing in and start with a platform you would be happier with....

So just because this isn't a Fox body or a RX7 or some other vehicle that somebody swaps an LS engine into, I don't have the right to do it? There is no difference here except it has the wrong LS drivetrain for my liking. I'll just do what you say because you say to and to hell with what I want to do with my vehicle. Wow indeed.

Refer to paragraph 2 of post #1

**Z28dryva** · 02-11-2013, 04:46 PM

I suppose with this logic that a guy with a 69 Camaro that wants to do a LS swap on his muscle car is stupid and should instead just buy a 2012 Camaro and quit coming up with stupid ideas

**pajeff02** · 02-11-2013, 05:12 PM

My little 5.3 backed by a 4L60E in our 2007 Suburban hauls my car trailer up and down the hills of Pennsylvania without any problem -- around 13,000 lbs in all. For the work involved in the proposed swap, I agree with FBJ, a new truck would be the way to go.

**Firebirdjones** · 02-11-2013, 06:55 PM

Won't get much help around here with an attitude like that Ryan. Since you have all the answers and seemed to have your mind made up before you even started this thread, then by all means, dive in and have fun. I wish you luck