Longshot.... T45 swap

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Dec 30, 2025 | 07:15 PM
  #1  
I am in the process of LS swapping my 87 GTA. I bought the car as a roller but it was originally a 305/t5 car. I plan on dropping in a stock lq4 and T45 transmission. Mainly will just be a cruiser.

I know t56 is the go-to but I don't have one. I do have a T45 (1381-000-011) from a 2000 mustang and I came across a guy who makes t45 to LS adapters.

I haven't mocked anything up yet but was hoping someone else has maybe done this before. The trans mount pad doesn't look too far off from a t56 and from what I can tell the shifter location looks close to the T5

I will need to figure out the crossmember and then a driveshaft. The trans to engine side should hopefully be covered.

Any tips on making this setup work would be appreciated!




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Dec 30, 2025 | 08:19 PM
  #2  
Re: Longshot.... T45 swap
Theres someone on this board who did it. The shifter was up by the ashtray. An adaptor was used to get it in the stock spot. The DS/yoke is pretty easy. You'll need a 10 spline clutch disk to work w the GM flywheel. It should be pretty easy. A custom x-member is easy and mount your torque arm to that. Speedo will need to get worked out.
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Dec 30, 2025 | 08:38 PM
  #3  
Re: Longshot.... T45 swap
that's good to know the stuff i'm stressing on might be simple and I'm just overthinking it.

I think I know the thread you are referring to, I think that guy used an AR5 and a remote shifter.

The T45 shifter location should be about 27" from the face of the bellhousing and the T5 is 27.5"
https://core-shifters.com/pages/shifter-distances

I also need to figure out a hydraulic slave, the mustang used a clutch cable. There's a conversion kit out there I will just need to see what everything looks like once it's mocked up in the car.
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Dec 30, 2025 | 09:03 PM
  #4  
Re: Longshot.... T45 swap
Good point, yeah different trans. You should be good w that.

A slave cyl mounted on the front bearing retainer would work really well. You can likely find a a stock(ish) master to actuate it.
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Dec 30, 2025 | 09:12 PM
  #5  
Re: Longshot.... T45 swap
I'll keep you posted on what I come up with.

I've been scouring the internet looking at different transmission dimensions and found that the mounting pad on a TH400 is 24" from face of bellhousing, 4L80 is 26", the T45 looks like 24.5" plus a 1/2" adapter plate so 25". TH400 crossmembers might be a good place to start and modify without reinventing the wheel
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