I have 2 GT'S a 69 and a 73 They appear to have different distributors the 69 has a seperate advance and retard vacuum unit, The 73 has a single double acting unit. The 73 also has a notch in which to lock the cap into the proper position. The 69 does not seem to have this feature. Question is do they both use the same cap and rotor or is the 69 a queer one.