If you’re reinstalling the front diff into the gearbox, see Corgiwerks comments below...
If you’re reinstalling the refurbed gearbox to the engine:
https://www.iwsti.com/forums/drivetrain ... ement.htmlYou want to turn the box or engine a bit, or change the angle of the engine, so the splines can match up and seat together.
If you have extra mating force from the bolts already installed, back them off a bit to give the assy some breathing space.
Iirc if the box is in a high gear, the unput is less likely to rotate when you turn the crank.
Rather than forcing it all together, you're trying to get both ends inline and offer them up.