Speaking from experience with 3 US OEM kit the US radios have all been poor because they only have the odd decimals on the FM band. So, my local Heart station is on 97.2 so I cannot/could not pick it up in the two Camaros and the Corvette.
Dont know if this helps, but I got the original 1965 radio in mine converted by a company in Bristol(?). It now has AM/FM, 4 x 45w output and MP3 input. Works great, and nobody can tell its not original.
Thanks for the thoughts guys.. I think that clarifies the U.S. Vs. UK FM issue... Will try to get a 'Euro compatible' one.. Although I'd be interested to understand how expensive the upgrade of an original unit might be?
