I picked up a 4T65E-HD transmission from a PFF member earlier this year and they did not know what car it originally came out of. The transmission does need a rebuild and the shop that is going to do it says they will help identify it the best they can by counting the teeth in the final drive gears and cross referencing the numbers on the tag. It looks to be an earlier version (pre-2003 I think) but my question is, am I still going to run into possible issues when I install this and have the ECU programmed by not knowing exactly what it came out of or will knowing the internal specs of the trans be enough to get the ECU programmed properly? I was also considering on having a shift kit installed if that has any impact on the topic. Total price for a rebuild and the installation of a shift kit will be a little over $1,500 on a loose hanging transmission.

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87 Fiero GT 3.4 Pushrod with 7730 ECM & DIS
88 MERA #8013
85 Fiero SE with 3.1 pushrod
86 Fiero SE 2.8 stock
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All 2003-earlier 4T65-E HD transmissions had the same overall final drive ratio: 2.93 (3.29 ratio diff with a 37/33 chain sprocket ratio).

2004 is when things changed for the 4T65-E HD. Besides most having the common 2.93 final drive, GM also made them available with an overall final drive ratio of 3.29 (3.29 ratio diff with a 35/35 chain sprocket ratio), and also made available the TAPShift (KB7) option for some of these transmissions.

The main thing you need to be concerned about besides gear ratio is what the model year of the transmission is. If it is a 1997-2002 transmission, then they are basically all the same as far as the PCM's programming is concerned. But 2003-newer 4T65-E's are different, electrically; and they won't work with 2002-earlier PCMs.

Yes, gear ratio is still a concern. The PCM tune needs to be set up properly for whatever overall final drive ratio the transmission has in it.

-ryan

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More is more. Less is not enough.

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You've got some work to do. As per Ryans post above it is imperative that you match the transmission to the PCM that has the ability to shift it. The earlier 97-02 transmission have three bolt stanchions on the passenger side while the later 03-up 4T65eHD's have only two. Also remember that the 4T65eHD and 4T65e are very similar in appearance. The HD version has a larger differential housing.
The only exception to this transmission family rule might be the 4T65e used on the 3800 N/A cars in 2008. That year GM changed over to a CAN BUS PCM . I'm not sure how this affected the internal workings of the transmission but with this type of interface, many elements have a separate IP address. This trans may only work with that computer.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: The earlier 97-02 transmission have three bolt stanchions on the passenger side while the later 03-up 4T65eHD's have only two.

Got any pictures you can post of this showing the differences?

quote Originally posted by Dennis LaGrua: Also remember that the 4T65eHD and 4T65e are very similar in appearance. The HD version has a larger differential housing.

The differences in the differential housing between HD and non-HD are so subtle the two may appear identical to the untrained eye.

quote Originally posted by Dennis LaGrua: The only exception to this transmission family rule might be the 4T65e used on the 3800 N/A cars in 2008. That year GM changed over to a CAN BUS PCM . I'm not sure how this affected the internal workings of the transmission but with this type of interface, many elements have a separate IP address. This trans may only work with that computer.

Whether or not the vehicle had CAN-Bus data communications has nothing to do with internal 4T65-E electronics. As far as I understand it, all 2003-newer GM 4T65-E transmissions are identical, at least electronically speaking. The only difference would concern the module that controls this transmission. Most CAN-Bus vehicles had separate TCMs (transmission control modules). All 3800 applications thru the end of 3800 production used one PCM to control the engine and transmission, most all others switched to using a separate TCM starting around the 2005 model year.

quote Whether or not the vehicle had CAN-Bus data communications has nothing to do with internal 4T65-E electronics. As far as I understand it, all 2003-newer GM 4T65-E transmissions are identical, at least electronically speaking. The only difference would concern the module that controls this transmission. Most CAN-Bus vehicles had separate TCMs (transmission control modules). All 3800 applications thru the end of 3800 production used one PCM to control the engine and transmission, most all others switched to using a separate TCM starting around the 2005 model year.

I have no information that can dispute this statement so I am not debating it. However if you notice the final year (2008) that the 3800 was used, GM went to the CAN BUS; there is no programming support on that PCM that I can find. As you may know the CAN bus interfaces with everything on the vehicle from the radio, A/C system to the window motor control.
The HP Tuners editor won't work for this one model year. If the 08 4T65e shift solenoids are receiving the same pulse width modulation signal that comes from the 03 PCM it should work but no one that I spoke to can provide a definite answer. A trans guy like Tripleedge should know for sure or anyone that has used the 08 trans. .

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: I have no information that can dispute this statement so I am not debating it. However if you notice the final year (2008) that the 3800 was used, GM went to the CAN BUS; there is no programming support on that PCM that I can find. As you may know the CAN bus interfaces with everything on the vehicle from the radio, A/C system to the window motor control. The HP Tuners editor won't work for this one model year. If the 08 4T65e shift solenoids are receiving the same pulse width modulation signal that comes from the 03 PCM it should work but no one that I spoke to can provide a definite answer. A trans guy like Tripleedge should know for sure or anyone that has used the 08 trans. .

All 4T65-E shift solenoids are simple on/off solenoids. They were never PWM (pulse width modulated).

Dave at TripleEdgePerformance would know for-sure if any changes were made to the 08 4T65-E's, but I don't think any were made from the previous model year (2007).

[This message has been edited by Darth Fiero (edited 08-01-2015).]