I'm building a Celica C60 gearbox for a MR2 Spyder. The second gear and No. 1 sleeve are damaged from grinding the gear. However, the No. 1 sleeve in the MR2 C65 box is good, but it has an integrated reverse gear (see attached picture). Fitting it would result in a mixure of reverse gears from the two boxes. Could mixing these gears cause problems.