So, ive been planing on upgrading the speakers on my mk1 estate, and noticed that there are empty slots for rear speakers. Just wanted to know, what are the sizes that fit, both front speakers and rear (the oval ones)?

Rear speakers at 6”x4” iirc the fronts are 6 1/2”. The rears are inside the plastic trim that runs down both sides of the rear 1/4 glass.