Syntrax works very well in Scoobys, but you can get better
75w-90 Gear oil
Silkolene Silktran Syn 5 is great stuff if the gearbox is in good condition, if not any wear can become more obvious when using it. Motul Gear 300 and Redline Lightweight Shockproof are good if the gearbox has been showing some wear.
You also get 10% off for being a Scoobynet member
Cheers
Tim