I was wondering if anyone knows if a V8 input shaft can be swapped in for the smaller spine v6 one on a world class t5 off a v6? I havew one sitting here and I am trying to sell it because it has like no miles on it but it has the v6 spline. I am told that the gear box is the same and that it's just the shaft thats different. I talked to someone at Hanlonmotorsports.com and they said it can't be changed, but I think it can. Anyone ever attempted this?

 

No they can't be swapped. The tooth count is different as the V6 input shaft has fewer teeth to allow for more initial gear reduction to the countergear shaft...this is how the first gear in the V6 T5's gets its lower (higher numerically) ratio. This also gives the V6 units their reputation for being weaker because that greater initial gear reduction multiplies the torque fed through the rest of the gearing - moreso than a V8. The same way that a 3.73 rear gear 'feels' more powerful than a 2.73 rear - the same power is being multiplied at a different rate.
The aluminum case isn't strong enough to handle that extra stress.

Pete

 

You can swap it if you also have a V8 countergear. The rest of the trans is the same; gears, mainshaft, case, etc.

For the amount of money and effort it would cost, you can get a whole working V8 trans. Don't bother trying to sell the 6-cyl trans; nobody cares.