any driveline/engineering shop will make one if you take them the yoke to suit supra. 3.08 will be an OK ratio. wouldn't want to go any taller. i had a 2.78 and it was rubbish until you got to 5th on the highway. 3.55 was too lively. I reckon 3.36 would be perfect. I don't know if mine was W57 W58 or other Supra mind you. they have different gear ratios. you'll need a modified cross member, a bell housing and a speedo drive i think.