Immo wont be affected, they're all interchangeble between mk1 and mk1.5. Clocks will be diff. So take note of the current if you have it and you can get it declared at next MOT.

Some people will charge a pretty penny to set the clocks to your current if you're bothered.

Those 1.5's were recalled because of water / condensation sitting on the PCB if memory serves me right. You might get lucky by reflowing the solder points on the back and applying some WD40 / PCB clear coat. - Check for skid marks & funny smells on the board to identify if it's blown any components.