Mid to late 80s GT Vertigo or Performer. Post a pic on BMX museum in the name it section and you'll get a definite answer. Include the serial, should be on the dropout or maybe the BB.
Can any one tell me what kind of diamond back this is I think its a formula 1 but not sure or what yr I put the 3piece cranks on it nothings original I'm just curious on wht frame it is