DEX 210 Gearbox Noise Under Braking

[Bizz]

Hey guys, had my first race in 15 years last night with a dex210 rtr, great fun and feels like the bug has bitten again! The chassis is much better than I am without doubt, I've ordered a stick radio as the wheel one just isn't for me and I broke a hanger which a replacement is now on its way but can't wait to race it again.

I did notice a noise coming from the gearbox under hard braking which sounds terrible, I'd relate it to a ball diff slipping but I'm on a geared diff.

Under acceleration with a 7.5 no bad noises whatsoever, will be stripping the car tomorrow which should answer the q but any heads up on what this could be would be much appreciated