Hi guys. Just bought a double din head unit to replace the stock unit for my series 1 au fairmont. The unit i got is a jvc Kw-r500. I got the stock head unit out no worries at all, slid streight out using the tools i got off ebay. However, the problem im having is that the new head unit wont slide in at all! The new unit is approx half a cm taller than the stock one and there are two corner bits on the dash surround that seem to be stoping it from going in.
The only way ive been able to get it in is to remove the dash surround. Is there something im doing wrong? I though din was a universal standard, shouldnt the unit slide right in? The only way i can see getting it in is to cut the corner bits at the bottom of the dash surround.

Also once and if i get it in, how do i fasten it in? The original had clips on the side to stop it sliding out, this one does not?

Any help greatly appreciated