Muscle bike identity help

[D0ZX]

Can anyone tell me what year this is? Where would I find numbers on it?
Thanks

 

[30thtbird]

I believe it's a Ross made bike. It's at least a 1971 or newer. The BMA sticker tells me that. Look on the rear dropouts bu the axle nut for a serial number and post that. We can go from there. Kenny.

 

[D0ZX]

Thanks Kenny
I removed the flag holder and the s/n is K71 129861, so I guess it's a 71?
It has a Ross decal but is missing the head badge.