I have an '88 firebird formula with a 305tbi, 700r4. Will this have an electronic or mechanical speedo?? When did they start electronic speedo?

should be a electric speedo, jack the car up and look at the driver? side of the trans. if there is a cable comming from the tail housing its mechanical, if there are wires its electric

Ok... now say I have a manual t-5 with mech. speedo to put in the car.. What must I do to convert this??

You need to find a T5 from an 86-89 Firebird with the 2000 pulse electronic speedo. Camaros didnt get electronic speedos until 1990 and after that they were all 4000 pulse.