You are talking about 2 different things.

IIRC
1. F-37 detuned the engine ECU a bit to reduce HP and torque and did about the same to the TCM to raise the shift point speeds and if needed replaced the torque convertor with the 2n gen OEM not the Euro unless you paid for the part. NOTE - some that had the F-37 done only got the ECU reprogramming as the mechanic "forgot" to do the TCM part.
2. The GDE ECU tunes overwrite the ECU tune such that any F-37 ECU detune is effectively gone but the TCM F-37 shift points, if there, do not change. If you want to get rid of F-37 shift points you have to get one of the GDE TCM tunes.

If you got a GDE TCM tune, which lowers the shift speed and fiddles with lockup, and did NOT also get a GDE ECU tune then you would have the lower F-37 HP and torque so in that situation, assuming all other systems are working correctly, I suppose you could experience some lugging. How much if any I don't know. For a while I had the F-37 ECU detune but my TCM did not have the F-37 shift points and I experienced no lugging but unfortunately what towing I did was under 2,000 lbs on dead flat N. Florida roads.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

papaindigo,

As always, your a wealth of information and a very big help! Thx for clarifying this for me, I never was quite sure how things equated in the ECM/TCM F37 vs GDE. I do have both GDE-flavored ECU's and took the opportunity to re-install the TCM tune last night while inspecting all elements of the intake (no issues found), cleaning the turbo (brake cleaner & compressed air) and vane actuator (tested OK, lubed up). Interestingly, the Jeep felt much zippier this AM, and kickdown/boost worked as expected when flooring it... Bad F37 TCM? Bad learning procedure? Not sure here, but I will test the tuned TCM over the next 2 weeks, as I will be traveling around with the camper, so as to get a definitive view of its behaviour when pulling a load...

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RIP 10/31/2012
Green Metallic 2006 CRD Limited
GDE Hot tune ~ Pre-F37 TCM ~ Transgo shift kit ~ MagnaFlow ~ Homemade Provent ~ OME 2" lift & Airlift ~ Samco ~ Euro TC ~ Lift pump ~ Nylon fan blade & Hayden clutch ~ Etc!

are you still testing? Is the tcm tune going up for sale?

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05 CRD Limited
GDE Hot Tune
Samco CAC Hoses
OME 790 and Bilstein 916 up front
OME 948 and OME N132L in rear
245/75/16 Treadwright Warden A/T on Richard Cepek DC-2
Euro torque converter
Renegade roof lights
Pioneer Z110bt double din navi w/ reverse cam

Whoaaa, kinda forgot about that one

Actually traded it and now have the original pre-F37 TCM, which I prefer for my type of driving... Now, I should edit this title!

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RIP 10/31/2012
Green Metallic 2006 CRD Limited
GDE Hot tune ~ Pre-F37 TCM ~ Transgo shift kit ~ MagnaFlow ~ Homemade Provent ~ OME 2" lift & Airlift ~ Samco ~ Euro TC ~ Lift pump ~ Nylon fan blade & Hayden clutch ~ Etc!

Im selling my CRD so could sell my GDE tuned TCM. However I need a stock one in return. If you can afford to be down a couple days for shipping let me know. $200 plus your TCM in return and its yours. (you pay shipping from Montreal) Or take a drive up seeing as NY is not that far

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2007 Grand Cherokee CRD, GDE ECO and DPF delete.
2006 CRD Limited, GDE ECO Full TQ and TCM tunes. SOLD