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Hi guys... new member here with what I hope is a super easy question.
I have a '91 Z28 that I've already swapped a '03 Suburban 5.3L into. (engine is running great) I'm now looking to put the transmission in and have located a 4L60E out of a '97 Trans Am. (RPO code M30) Will these two mate up correctly without having to swap out any of the internals? I know there are differences in the input shafts, etc...
I did some searches, but I just wanted to be 100% sure before I bought anything. Transmissions are going ridiculously fast around me.
The '97 4L60E will be of the "298mm input shaft" type. The matching torque converter will therefore have too short a pilot to reach the LS engine's crank. No problem - bolt the GM spacer onto the end of the crank.
Next the converters mounting holes will be about 1/8" different from the holes in the LS engine's flexplate. No problem - enlarge the holes a bit. Unless you want to buy a new flexplate; maybe $100 for a decent one.
Presumably your swapped engine came with the PCM and harness to plug into a 4L60E. '96 thru '06 4L60E/4L65E are electrically compatible, so that should be fine.
Now, despite my "no problem" comments, the '97 is a 25 year old transmission designed for a much lower power engine than your LS. Unless it was recently rebuilt with upgrades, it might not last very long. You will be better off getting a 2001 - 2008 4L60E/4L65E which will bolt right up and have some factory upgrades to handle LS power.
OK. I picked up the new transmission and everything looks like its in pretty good shape, just a couple things that are confusing me...
- The new transmission has a "lever" looking gear shift selector, whereas the stock '03 trans had an entire electronic assembly that fit over the shaft. Are these interchangeable?
- The paper ID tag was removed/missing, I found this code (7FFD202B) stamped into the passenger side of the case, but for the life of me I can't find a decoder.
OK. I picked up the new transmission and everything looks like its in pretty good shape, just a couple things that are confusing me...
- The new transmission has a "lever" looking gear shift selector, whereas the stock '03 trans had an entire electronic assembly that fit over the shaft. Are these interchangeable?
- The paper ID tag was removed/missing, I found this code (7FFD202B) stamped into the passenger side of the case, but for the life of me I can't find a decoder.
A 1997 F-Body has that "electronic assembly" (Automatic Transmission Park-Neutral Position and Range Switch Assembly) inside the car with the Gear Selector/ Shifter.
Your 1991 F-Body has this switch under your center console by the Gear Selector if it is originally a THM700-R4 vehicle.
If the Selector Shaft is too short to fit the switch on the outside of the Transmission... the Selector Shaft can be changed to a longer version.
Thanks for that info @vorteciroc I'm not sure I understand your second answer though...
My question is - are the '03 PNP assemblies interchangeable on the '97 1-piece 4L60E case I now have? I kept all the '03 wiring for the Trans in my harness, so I'd like to keep it as close to factory as possible.
It sounds like you are saying yes, I'd just need to remove the additional factory '91 trans switch/wiring in the cabin. Is that correct?
My understanding of Vorteciroc is that your '91 has the Park/Neutral safety switch and Reverse-lights switch built into the in-car shifter. Therefore you don't need the electrical box on the side of the trans. Just connect the shifter cable to the lever on your trans.
The '03 engine harness should plug right into the trans and that should be all you need.
Now, if you cannot key the starter motor or your reverse lights don't work, some additional debugging will be needed.
For your 298mm 4L60E you will need to add the GM spacer after the crank and flexplate. GM spacer part #12563532; you also need 6 longer bolts #19257940. See post #1 of this sticky: https://ls1tech.com/forums/automatic...s-spacers.html
That's a great writeup. Thanks for pointing me to it @mrvedit It clarified a lot.
I guess I'm still a bit confused on this Park/Neutral switch issue though. My engine harness from the '03 has both the PCM connectors for the trans solenoids and the Park/neutral connectors - which will need to be plugged into *something* in order for the ECU to see that it's ok to allow the vehicle to start. (ie... that its in park or neutral) If I remove the switch from the trans I'd have to hack these into the shifter level wouldn't I? or somehow "trick" the ECU into thinking its parked when its not? (bypassing an important safety feature)
This could just be two ways of accomplishing the same outcome, but it seems much cleaner and straightforward to use the LS harness into the Park/Neutral switch (assuming its interchangeable) and just keep a mechanical connection from shifter to trans.
NCFarmLife, you seem to be understanding this fully now.
I don't know what the requirements of your '03 PCM are, but my '02 PCM could read the Park/Neutral signal but didn't seem to use it. So my car would start in any shifter position; I could not find a tuning option for that in the PCM.
In many cars, the ignition switch "Start" connects through the Park/Neutral switch before reaching the starter motor. My reading of Vorteciroc is that this Park/Neutral switch is built into your shifter. Similarly my B&M shifter has such a switch which I connected to my '02 (411) PCM, but it had no effect. I now have the Holley Dominator ECU and I think that does read the Park/Neutral signal and will prevent a start when in Drive or Reverse. Hence I don't know what your '03 PCM will do.
I understand that, if necessary, you don't want to swap to a longer trans shift rod after the trans is installed. If your current starter circuit goes through your in-car shifter, you should be safe. We can always Ground the wire to your PCM later to make it think you are in Park/Neutral in case it won't let the engine start (but your starter cranks).
Appreciate your patience in explaining. It's always hard to work through these explanations over the internet.
That's weird that your PCM doesn't seem to use the Park/Neutral signal. On mine, I had to have the connector jumper'ed temporarily to allow it to start since the trans wasn't installed yet. I'm going to pour over these wiring diagrams again for awhile to make sure I understand everything 100%, but it sounds like the interior circuit will be redundant and is OK to remove.
Op just take the Park/Neutral switch from your old trans and bolt it to the one you want to use now. If the shift selector shaft is too short swap it from the old one. To change out the shift selector shaft all you have to do is remove the pan, pry the spacer clip from the shaft and undo the nut that holds the rooster cone to the shaft. Then pull or tap the shaft out of the case. Be very careful not to drop the nut down into the case.
Last edited by bbond105; Mar 10, 2021 at 02:18 PM.
Op just take the Park/Neutral switch from your old trans and bolt it to the one you want to use now. If the shift selector shaft is to short swap it from the old one. To change out the shift selector shaft all you have to do is remove the pan, pry the spacer clip from the shaft and undo the nut that holds the rooster cone to the shaft. Then pull or tap the shaft out of the case. Be very careful not to drop the nut down into the case.
Perfect. Excellent explanation bbond. Thank you!
I watched an entire 4L60E rebuild series during COVID on Youtube, so I've seen exactly how to do this. I need to drop the pan to replace the filter anyway, so I can take care of it then if necessary. Unfortunately, the Park/Neutral switch from my '03 was glued in (factory assembly) and so to get it out without having to cut the harness I had to destroy the switch. Luckily, the replacements are cheap $20-$50 and as far as I can tell a direct replacement.
The Early style switch assembly has two electrical connectors...
They are sold with or without adhesive preinstalled on the electrical connectors.
If anyone here rebuilds these instead of purchasing "Pig-Tails"...
I will go and look up the Delphi part numbers for the different electrical connectors (with or without adhesive).
Non-Adhesive Connector part numbers are as follows (Delphi part numbers, NOT GM/ Delco part numbers).
Purchase these from Mouser.com if you do not have a Delphi account.
You guys are the absolute best! Thank you so much for the quick and concise answers - I never would have made it this far without help from individuals like yourselves.
Transmission is in! (what a chore doing this by myself is, but I finally got it done)
Just waiting on a couple odds n' ends to finish it up enough for her first roll out of the barn in almost 2 years!
Question about 4L60E transplant 
