Double Round vs Rectangular Tail Lights

[Straversi]

This has probably been asked and answered a hundred times but can anyone tell me difference between the double round tail lights FFR uses and the single rectangular tail lights used by others?

I've seen builders replace the FFR lights? Is one style more authentic?

[sl1993r]

Is one style more authentic?

Nope. Both styles were used.

[Gumball]

Rectangular lamps were used from the beginning on the original cars and for the early 427 versions. The later cars in the production line used the round lamps.

So, from an originality perspective, rectangular works on both the 289 and 427 body style, but round works only on the 427 body style.

[Straversi]

Thanks