A few other kits have been made by manufacturers such as Revell and Testors back in the day. The Revell one was quite nice, it came with a convertible top if I recall correctly.
There may seem to be an issue with this particular model in that it has a hard top... not so. In Part II, where the most iconic '46 Ford scenes take place, a stunt car used in the tunnel chase scene had a hard top that was chopped off and replaced with convertible hardware. This vehicle can still be seen shined up at Universal Studios Hollywood.