[twobjshelbys]

They "ran out" of 4xxx numbers and started with 6xxx. Other than that the cars are the same. There are some evolutionary changes and options that may or may not be available any longer, but there are no significant differences.

Older fibreglass 4xxx series cars are thought to be "superior", especially if you can find one that is pre-Hi-Tech (same manufacturer as Superformance, but not the same car). Especially the ones from HST. Mine was a carbon fiber HST car and I thought it was gorgeous. The quality of the body work was perfect.

Same for alloy body cars - early 4xxx alloy cars were built in house, starting at some point they were built by Kirkham (but were different from Kirkham), and at some point the alloy 4xxx/6xxx became just a Kirkham pulled off the line to get a CSX number.

Any of them will serve you well. I still say they were of the highest overall quality of all of the replicas.