4 speed Gearbox interchangability

[Angle Grinder]

I have a 1967 PF Coupe with the later improved design of gear selector mechanism.

Unfortunately, the box is rather noisy and I suspect layshaft bearing are on the way out. Everything else about the box is fine and changes very sweetly with no synchro issues.

I have obtained a replacement box which has been stripped of its gear selector mechanism. The replacement box is of the earlier design and it looks to me as if the differences in the gear selector yokes are going to be an issue.

The later models have a selector yoke that is topped by a sort of comma shaped "plate" into which inserts the gear selector "prong" that moves the selector yoke up and down. Also the linkage of the fore / aft gear selector rod attaches on top and inboard.

The earlier model box has a selector yoke that is topped by a simple circular shaped plate into which inserts the gear selector "prong" that moves the selector yoke up and down. And the the linkage of the fore / aft gear selector rod attaches at a point which looks like it will interfere with the later style of  "prong" for moving the selector yoke up and down.

I'll try to take pictures to explain, but maybe somebody on here has experience of swapping these gearboxes from early / late models of 1.8 PF Coupe.

I'm guessing I'll need to try to source the whole gear selector mechanism for an earlier model.

[Angle Grinder]

This is what concerns me, the distance from the shaft of the selector yoke to the linkage road is ~15mm on the replacement box which has the earlier gear selector mechanism.

[Angle Grinder]

But on the original box the "prong" extends ~25mm / 1 inch beyond the shaft of the selector yoke so it will not be possible to mate this gear selector mechanism from my later box onto the earlier replacement box as it will hit the gear linkage, unless i get out the angle grinder and cut ~10 mm off the prong, which I don't want to do as thelong term objective is to overhaul the original gearbox to refit.

Has anyone got an earlier series of gear selector mechanism that they could sell?