Here is how you can tell, notice the brake cable on the top tube , it as a full outer , the SB as open brake cables, the stem is Cinelli 1A the other is a 1R, Cinelli 66 on the Henk 64 on the SB5990. Wheels are built on Gp4s where as SB5990 is MX18 all other parts are period correct for 1983 :lol: