Coincidentally I just finished installing this goodness
https://legacypic.uk/infopages/transmis ... ty754vbaaaAnd now my clutch slips.. Let's hope it is just a bit of contamination that will burn/wear off. I recall last time I pulled and reinstalled the gearbox it also slipped for a short while under heavy load.
EDIT: As I expected, after more city driving the clutch does not slip anymore. Just came back from a half an hour blast on the roads - new box and lsd feels amazing!
Would be interesting to know what causes this slipping phenomenon after pulling the clutch basket off. My bet is on possible dirty fingerprints left on the surfaces.
If your using a different flywheel then it just needs some time to seat, theres also probably some oxidation on it