To TR3650 or to not TR3650


Active Member
Aug 5, 2020
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Ok so this may be long winded... but here it goes. Most of you know I've got a cobra with the T-45. Trans is fine and doesn't have any issues. Now i have the ability to pick up (for free) a Tranzilla Tr3650 from Rockler gear. Has upgraded 2nd gear and a better synchro package. Sort of an OEM+ type build. Trans was in a vehicle for a few months until the input shaft snapped. So regardless of what choice is made, its going to need a new input shaft. I would most likely have to pay for parts and labor on the trans, unfortunately no favors owed at this time lol.

I came by the trans because my in laws own a transmission shop. A kid brought the car in for a new clutch and trans. A few months later snapped the input shaft on a brand new trans. they kept the trans incase an investigation was needed etc. Well 10 years later its sitting on the shelf still. So I've got a couple options on what to do.

1. leave it and throw it away.
2. Replace the input shaft and swap into the cobra. This would require a clutch, shifter and some way to rig the speedo since they are manual vs electronic, a different way of mounting since the mounts on a GT and cobra are different.
3. Replace the input shaft and trade/sell it for a profit. spend the money on something else.

a 4th but not really an option at this time, take it apart. replace with carbon synchros, have all the gears and shafts cryo treated, install a 26 spline input shaft and have a 600 to 700hp capable trans. this most likely is not in the budget.

I'm leaning towards selling it as it is the simplest option.

Randall Garner

New Member
Mar 17, 2019
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Your drive motor will work for your speedo. May need to change the gear on it. To get it to show correct speed. I put a c-6 in a 98 and fit the electric drive into the c-6 works just fine. Had to change gear teeth to get it closer. Price the parts to fix that trans. And what ever necessary accessories. Maybe get family assistance on you doing labor they supervise . Put it in and enjoy the better gear and performance.

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